Query String


A query string is a section of a URL that contains specific data to be passed to web applications. It typically follows the main URL and starts with a question mark (?), with various parameters separated by ampersands (&). These strings are often used for tracking purposes and to provide dynamic content within websites.


The phonetics of the keyword “Query String” would be “KWE-ree string”.

Key Takeaways

  1. Query strings are a part of the uniform resource locator (URL) that assigns values to specified parameters. They are usually used to pass data and information between web pages.
  2. In the URL, a query string typically starts with a question mark (?) followed by the key-value pairs, which are separated by ampersands (&). It’s also important to remember that each key-value pair is separated by an equals sign (=).
  3. They play a significant role in tracking and analytics as they can be used to record data about the user journey. However, too many or unnecessary query strings can slow down website loading times and complicate data management.


A query string is a crucial part of web technologies and plays a significant role in providing a flexible, data-driven user experience. Query strings are part of the URL that come after a question mark and contain key-value pairs. These pairs can carry information which can be used to filter data, track session state, pass parameters, or control the functionality of the webpage. This makes them an important tool for creating dynamic, interactive web applications. The ability to change content based on query strings allows developers to build more adaptable user experiences, hence their importance in the field of technology.


A query string is a part of a uniform resource locator (URL) that assigns values to specified parameters. It fundamentally allows users to retrieve and also deliver specified data from a database. In other words, a query string makes it possible to pass information from one webpage to another, or from a website to a server, usually in response to a user action. Think of it as a tool for getting or sending very specific information based on the configured parameters.Web applications frequently use query strings to personalize content or to track user behavior. For example, when you conduct a search on a search engine, the text you type in becomes part of the query string which the search engine uses to look up related information. Similarly, in e-commerce scenarios, when you select a specific product to view, the Item ID is typically passed as a query string to retrieve the right product data from the database. So essentially, they provide a flexible means for web users and servers to exchange information.


1. Google Search: When we type in a keyword for searching on Google and press ‘enter’, the keyword is added in the URL after a ‘?’ marking the beginning of the query string. So if you type “technology” in the search bar, your browser’s URL will show something like: Here, “q=technology” is the query string.2. E-Commerce Websites: On websites such as Amazon, when users filter products by certain attributes such as price, brand, etc., the URL in the address bar changes to include these filter parameters as part of the query string. For example, if you are searching for “laptops” and select the brand as “Dell”, the URL might look like this: The part after “?” is the query string where the parameters represent your search keyword and filters.3. Social Media Platforms: On websites like Facebook and Instagram, when you’re viewing a particular post, the URL will include a query string that identifies that specific post. For example, in Instagram, the URL could be something like, where the sequence after “/p/” is essentially a query string that identifies a specific post in their database.

Frequently Asked Questions(FAQ)

**Q: What is a Query String?****A:**A query string is a part of a URL that contains data to be passed to web applications such as a search engine or other website. It typically comes after a “?” in a URL and can contain multiple parameters separated by “&”.**Q: How does a Query String work?****A:**A client sends a query string as part of a HTTP request to a server. The server then processes this information and returns the appropriate data. This might involve searching a database for specific information, updating data, or requesting a specific view of a website.**Q: What does a Query String look like?****A:**A typical query string might look like this: ``. The ‘?’ precedes the query string, and parameters are separated by ‘&’. The ‘=’ sign is used to assign values to parameters.**Q: Are Query Strings case-sensitive?****A:**Yes, query strings are typically case-sensitive, both for the parameter names and their values. That means ‘query=example’ would be different from ‘QUERY=EXAMPLE’ or ‘Query=Example’.**Q: Is there a limit to the length of a Query String?****A:**There is no defined limit in the HTTP/1.1 specification, but most browsers and servers impose a practical limit. Generally, to ensure compatibility across most systems, it’s advised to keep query strings under 2048 characters.**Q: Can Query Strings contain special characters?****A:**Yes, but they may need to be URL encoded depending on what the characters are. URL encoding replaces unsafe ASCII characters with a “%” followed by two hexadecimal digits corresponding to the character in the ISO Latin character set.**Q: Is it safe to pass sensitive information via a Query String?****A:**No, it’s not recommended to pass sensitive or private information in a query string. This is because query strings are easily visible and can be stored in browser history or server logs. For sensitive information, methods like HTTP POST with SSL should be used.

Related Tech Terms

  • URL Encoding
  • HTTP protocol
  • GET Method
  • URL Parameters
  • Web Server

Sources for More Information

  • W3Schools:
  • MDN Web Docs:
  • GeeksforGeeks:
  • Stack Overflow:

About The Authors

The DevX Technology Glossary is reviewed by technology experts and writers from our community. Terms and definitions continue to go under updates to stay relevant and up-to-date. These experts help us maintain the almost 10,000+ technology terms on DevX. Our reviewers have a strong technical background in software development, engineering, and startup businesses. They are experts with real-world experience working in the tech industry and academia.

See our full expert review panel.

These experts include:


About Our Editorial Process

At DevX, we’re dedicated to tech entrepreneurship. Our team closely follows industry shifts, new products, AI breakthroughs, technology trends, and funding announcements. Articles undergo thorough editing to ensure accuracy and clarity, reflecting DevX’s style and supporting entrepreneurs in the tech sphere.

See our full editorial policy.

More Technology Terms

Technology Glossary

Table of Contents