Web Development Terms and Glossary in 2026
This glossary is designed for anyone who needs assistance figuring out what certain acronyms or web development terms mean. It covers a range of web development terminology, all of which is arranged in alphabetical order.
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100 Status Code (Continue):
A 100 status code means the server has received the beginning of the request and has not rejected it. The server expects the rest of the request to continue before it sends a final response.
101 Status Code (Switching Protocols):
A 101 status code means the server understands and accepts the client’s request to switch to a different protocol for the connection.
102 Status Code (Processing):
A 102 status code is an interim response indicating that the server has accepted the complete request but has not yet completed it.
200 Status Code (Ok):
A 200 status code means the request was successful and the server returned the requested resource or response.
201 Status Code (Created):
A 201 status code means the request was successful and the server created one or more new resources as a result.
202 Status Code (Accepted):
A 202 status code means the server has accepted the request for processing, but the process has not been completed yet and may or may not be completed later.
203 Status Code (Non-Authoritative Information):
A 203 status code means the request was successful, but the response content was modified by an intermediary, such as a proxy server, before being delivered to the client.
204 Status Code (No Content):
A 204 status code means the server successfully processed the request, but there is no additional content to return in the response body.
205 Status Code (Reset Content):
A 205 status code means the server successfully processed the request and expects the client to reset the current view or form to its original state.
206 Status Code (Partial Content):
A 206 status code means the server successfully fulfilled a request for part of a resource and returned only the requested portion of the content.
207 Status Code (Multi-Status):
A 207 status code means the server returned multiple status codes in a single response because the request involved multiple resources or operations.
208 Status Code (Already Reported):
A 208 status code means the server avoids repeating the same resource information multiple times within a multi-status response.
226 Status Code (IM Used):
A 226 status code means the server successfully processed a GET request and returned a modified version of the resource after applying one or more transformations.
300 Status Code (Multiple Choices):
A 300 status code means the requested resource has multiple available versions, and the server provides options so the client can choose which version to access.
301 Status Code (Moved Permanently):
A 301 status code means a page has been permanently moved to a new URL, and requests should be redirected to the new location.
302 Status Code (Found):
A 302 status code means a page is temporarily redirected to a different URL, but the original URL should still be used for future requests.
303 Status Code (See Other):
A 303 status code means the server redirects the client to a different URL to retrieve a separate response related to the original request.
304 Status Code (Not Modified):
A 304 status code means the requested resource has not changed since the last request, so the server does not need to resend the content.
305 Status Code (Use Proxy):
A 305 status code was originally used to indicate that a proxy server should be used to access the resource, but it is now deprecated due to security concerns.
307 Status Code (Temporary Redirect):
A 307 status code means a resource is temporarily located at a different URL, and the client must keep using the same request method when following the redirect.
308 Status Code (Permanent Redirect):
A 308 status code means a resource has been permanently moved to a new URL, and all future requests should use the new location while keeping the same request method.
400 Status Code (Bad Request):
A 400 status code means the server cannot process the request because it contains invalid syntax or another type of client-side error.
401 Status Code (Unauthorized):
A 401 status code means the request cannot be completed because valid authentication credentials are required to access the resource.
402 Status Code (Payment Required):
A 402 status code is reserved for future use and is not commonly used in standard web communication.
403 Status Code (Forbidden):
A 403 status code means the server understood the request but refuses to allow access to the requested resource.
404 Status Code (Not found):
An error message that occurs when what was requested could not be found. Broken or dead links often cause this.
405 Status Code (Method Not Allowed):
A 405 status code means the server recognizes the request method, but the requested resource does not support that method.
406 Status Code (Not Acceptable):
A 406 status code means the server cannot provide a response in a format that matches the client’s requested preferences.
407 Status Code (Proxy Authetication Required):
A 407 status code means the client must authenticate with a proxy server before the request can be completed.
408 Status Code (Request Timeout):
A 408 status code means the server timed out waiting for the client to send the complete request.
409 Status Code (Conflict):
A 409 status code means the request could not be completed because it conflicts with the current state of the resource.
410 Status Code (Gone):
A 410 status code means the requested resource is no longer available on the server and has likely been permanently removed.
411 Status Code (Lenght Required):
A 411 status code means the server requires a valid Content-Length header before processing the request.
412 Status Code (Precondition Failed):
A 412 status code means one or more conditions in the request headers were not met by the server.
413 Status Code (Payload Too Large):
A 413 status code means the server refuses to process the request because the request payload is too large.
414 Status Code (Request-URI Too Long):
A 414 status code means the server refuses to process the request because the URL is too long.
415 Status Code (Unsupported Media Type):
A 415 status code means the server refuses to process the request because the payload format is not supported.
416 Status Code (Requested Range Not Satisfiable):
A 416 status code means the requested range cannot be fulfilled because it does not match the available portion of the resource.
417 Status Code (Expectation Failed):
A 417 status code means the server could not meet the expectations specified in the request’s Expect header.
418 Status Code (I’m a Teapot):
A 418 status code means the server is a teapot, originating as an April Fools’ joke and occasionally used to reject unwanted requests.
421 Status Code (Misdirected Request):
A 421 status code means the request was directed at a server that is unable to produce a response for that connection.
422 Status Code (Unprocessable Content):
A 422 status code means the server understood the request but could not process it due to semantic errors in the data.
423 Status Code (Locked):
A 423 status code means the resource being accessed is locked and cannot be modified until the lock is released.
424 Status Code (Failed Dependency):
A 424 status code means the request failed because a previous request it depended on also failed.
426 Status Code (Upgrade Required):
A 426 status code means the server refuses to process the request until the client upgrades to a different protocol.
428 Status Code (Precondition Required):
A 428 status code means the server requires the request to be conditional to prevent conflicting updates to a resource.
429 Status Code (Too Many Requests):
A 429 status code means the client has sent too many requests in a given amount of time and is being rate limited by the server.
431 Status Code (Request Header Fields Too Large):
A 431 status code means the server refuses to process the request because one or more header fields are too large.
444 Status Code (No Response):
A 444 status code is a non-standard Nginx code that closes the connection without sending a response to the client.
451 Status Code (Unavailable For Legal Reasons):
A 451 status code means the server is denying access to the resource as a result of a legal demand.
499 Status Code (Client Closed Request):
A 499 status code is a non-standard Nginx code that means the client closed the connection before the server could send a response.
500 Status Code (Internal Server Error):
A 500 status code means the server encountered an unexpected condition that prevented it from fulfilling the request.
501 Status Code (Not Implemented):
A 501 status code means the server does not support the functionality or request method needed to fulfill the request.
502 Status Code (Bad Gateway):
A 502 status code means the server, while acting as a gateway or proxy, received an invalid response from an upstream server.
503 Status Code (Service Unavailable):
A 503 status code means the server is temporarily unable to handle the request due to overload or scheduled maintenance.
504 Status Code (Gateway Timeout):
A 504 status code means the server, while acting as a gateway or proxy, did not receive a timely response from an upstream server.
505 Status Code (HTTP Version Not Supported):
A 505 status code means the server does not support the HTTP version used in the request.
506 Status Code (Variant Also Negotiates):
A 506 status code means the server has an internal configuration error that prevents it from properly completing the content negotiation process.
507 Status Code (Insufficient Storage):
A 507 status code means the server is unable to process the request because it does not have enough storage to complete it.
508 Status Code (Loop Detected):
A 508 status code means the server terminated the operation after detecting an infinite loop while processing the request.
510 Status Code (Not Extended):
A 510 status code means the server requires further extensions to the request before it can be fulfilled.
511 Status Code (Network Authentication Required):
A 511 status code means the client must authenticate with the network before the request can be fulfilled.
599 Status Code (Network Connect Timeout Error):
A 599 status code is a non-standard code used by some proxies to indicate a network connection timeout occurred behind the proxy.
A
Accelerated mobile pages:
Accelerated Mobile Pages (AMPs) are stripped-down web pages with minimal HTML intended to optimize search results on mobile devices. Because of their minimal nature, AMPs can offer faster load times and less data usage, improving visibility on mobile devices.
Adaptive design:
A way to build a website with several different layouts suited for different screen sizes.
Algorithm:
A set of steps for carrying out specific tasks. When an algorithm is created, developers document all the steps needed to solve a problem and what each step involves.
API (application program interface):
How computers and applications communicate with each other.
Application (app):
A type of software that allows the user to perform different tasks.
Attribute:
Information about elements of a component in your website design/build
B
B2B web development:
The process of designing and creating a website that serves as an online space for your business-to-business company. Good B2B web development will help consumers learn more about your business and browse and purchase products more efficiently.
Back-end:
Everything going on behind the scenes, powering what happens at the front-end. There are four main components of a back-end development software stack: The server, the database, the operating system, and the software.
Bandwidth:
Bandwidth refers to the maximum amount of data that can be transmitted between the Internet and your site in a given amount of time. Having a larger bandwidth allows you to move data faster and can improve user experience.
Bootstrap:
A free, open-source, front-end framework for designing websites and web apps, developed by Mark Otto and Jacob Thornton at Twitter to encourage consistency across internal tools.
Browser:
Program used to access the Internet and display web pages. When you type a web address or URL into a browser, it sends out a series of requests. It gathers different elements that make up the webpage, like images, ads, and content to display the page.
Bug:
An error or flaw that prevents a website or app from running correctly.
C
Cache:
The storage of certain elements to create faster load times for repeat website visitors. If a change is made to a website, users will need to clear their browser’s cache to see it.
Classes:
An identifier in CSS for specifying what you want to target with styling. In other programming languages, classes are broadly used as a blueprint to create something.
CMS (content management system):
The program you use to create and maintain your website’s content. A commonly used CMS is WordPress.
Code:
What web developers write using programming languages.
Conversion:
Goals you have for things on your websites, such as email signups and downloads.
Cookies:
Data sent by an Internet server to a browser. Whenever the browser accesses the same server, it sends that data back to track how often it accesses the server.
Crawl:
Occurs when search engines send bots to your website to find out which pages exist and don’t exist to determine what content should be displayed or removed in search results.
CRM (customer relationship management):
Software and applications used to gather, analyze, and maintain information about customers, donors, and prospects.
CSS (cascading style sheet):
Code that tells browsers how to display a webpage to users. This programming formats fonts, colors, and other visual elements.
CTA (call to action):
Buttons on your website to drive specific conversions or goals, like a newsletter signup or a contact form.
D
Data structures:
A way to organize and store data for maximum efficiency. These make it easy to find, access, sort, insert, and delete data. Types include linked lists, stacks, queues, and sets.
Debugging:
The process of identifying and dealing with bugs.
Deployment:
When a website or app goes live after development and testing.
DevOps (development operations):
System that helps to keep development, IT operations, and quality assurance departments on the same page to make for better end-products and collaborations.
Domain:
The address for a website as entered into the browser.
Documentation:
Essentially the central point of reference for anyone involved in managing, maintaining, or using a website or piece of software. It may provide information on requirements, architecture and design, technical properties, data for the user, or marketing.
E
Ecommerce web development:
It is the process of creating a website that will be used to sell or buy products or services online. This can help to generate more revenue and conversions for your business.
Entreprise web development:
It is the process of creating and designing a website used by mid to large (enterprise) level businesses. This involves choosing the best structure for your site to deliver the best user experience.
F
Favicon:
Short for “favorite icon”; the icon that appears in your website’s browser tab.
Fields:
The most basic building blocks for data collection. They’re storage units that website visitors use to enter their names, email addresses, notes, etc.
Firewall:
System to protect a secure network from an unsecure network.
Framework:
Suite of programs used in website or software development lays the groundwork for the type of programming language used for your website or app development.
Front-end:
The part of the website or app that the user sees.
FTP (file transfer protocol):
Method of exchanging files from one computer to another.
Full-stack:
Full-stack developers work across all three layers: The front-end, back-end, and database.
G
GUI (graphical user interface):
The image of how a website is laid out and meant to be interacted with.
H
HTML (hypertext markup language):
Describes how an Internet browser should display a document as a webpage. It consists of tags, elements, and attributes.
HTTP (hypertext transfer protocol):
Used to transfer data across the Internet by sending data from an HTTP server program to an HTTP client program.
HTTPS:
HTTPS is an upgraded version of the network protocol standard HTTP. With HTTPS, websites create a secure online experience by encrypting data, like names, addresses, and credit card numbers, and ensuring its safe transfer to the site’s server.
HTTP status codes:
HTTP status codes are three-digit numbers that are returned by servers to indicate the status of a client’s request. When a client (such as a web browser) makes a request to a server, the server will respond with a status code and a message indicating whether the request was successful or not.
I
Information architecture:
The practice of organizing complex information clearly and logically. This means creating a user-friendly structure that makes it easy for users to navigate through websites and apps.
J
Java:
A popular programming language that is platform-independent and can be run on any device regardless of what operating system is used.
JavaScript:
Primarily used as a client-side language, embedded into the HTML of a page and sent to a browser. Web developers use this to add automation, animations, and interactivity to web pages.
jQuery:
A JavaScript library that simplifies the task of using JavaScript on your website by condensing several lines of JavaScript code into a single line.
M
Meta tag:
Additional information on web pages or elements, like the way a piece of content should display in Google search results, the credit for an image, or the main keywords associated with a plugin.
Minification:
The process of minimizing code and markup to reduce the file size.
Mobile-first:
An approach to web design and development that prioritizes mobile devices. The website is built first for a small screen, then for a desktop.
MVP (minimum viable product):
the most pared-down version of a product that can be released to the market. When adopting this approach, developers will focus on the core features and functions that are essential. Once the product is released and user feedback is gathered, they will continue to build the complete set of features.
MySQL:
The world’s most popular open-source database management system.
O
OOTB (out of the box):
Ready-made, plug-and-play options for features and functions that you can download and install without the need to customize or configure them.
Opening/closing tags:
Angle Brackets (< >) that bookend an HTML element to help build a web page structure. Closing tags include a forward slash (</>).
Operating system:
A type of software that enables the user to run applications on a device.
P
Page template:
The layout for a webpage. Pages that have similar structures share the same template.
PHP (hypertext preprocessor):
A server-side scripting language used to generate dynamic page content, send and receive cookies, control user access, and encrypt data.
Plugin:
An extension that adds extra functionality to existing software.
Property:
Characteristics that are dictated by CSS, such as color schemes and fonts.
R
Redirects:
Automatic forwards from one URL to another, usually from an old website URL to the same page on a new website.
Registrar:
Company used to register domains.
Resolution:
How large an image or graphic can be rendered on a display.
Responsive design:
Websites that accommodate the screen on which they’re being viewed.
S
SAAS platforms:
“Software as a service,” the most basic cloud platform that allows users to share files and collaborate on projects through their browser.
Server:
Computers running software that allows users to access your website and houses the hosting.
Sitemap:
An outline of all pages on a website organized in hierarchical order.
Slider:
Carousel of images usually featured on a site’s homepage that rotates, highlighting different photos, links, and content.
Software stack:
Bundles of software that work together to make up the back-end of a website.
SSL (secure sockets layer):
A standard security protocol for ensuring that all data transmitted between the web server and the browser remains encrypted.
T
Text editor:
A type of software used to write plain, unformatted text.
U
UI (user interface):
Visual elements that go into a website or app.
UX (user experience):
A user’s interaction focused on how satisfying and successful the experience is.
W
Web app:
Connect via the Internet browser and adapt to whichever device you’re viewing them on.
Widgets:
Applications that allow for specific interactive functions to be performed on a website.
Wireframe:
The bare-bones structure of a website.
WYSIWYG (what you see is what you get):
A visual content editor within CMS that allows you to modify content in your website without knowing HTML.
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