A query string is the part of a URL that carries extra information for a webpage, usually following a question mark (?). It's often used to pass data like search terms, filters, or user preferences to a site so it can display specific results. You’ll see query strings when you do things like search on a website or filter products in an online store. Though they’re usually short snippets, query strings can tell a website a lot about what the user wants to see.

How a query string works in a URL

A query string begins after the question mark in a URL and is made up of key-value pairs. For example, in example.com/search?term=shoes&color=blue, term=shoes and color=blue are parameters passed to the server. Each pair is separated by an ampersand (&). The server uses this information to return customized content, like filtered product listings or search results.

Most often, query strings appear when you submit a form, use search boxes, or apply filters on a webpage. They help developers deliver dynamic content without changing the actual page structure. They're also useful for tracking things like campaigns and referral sources through tools like Google Analytics.

Common uses for query strings

Query strings are commonly used for several practical reasons in web development:

• To track user behavior, such as where traffic comes from (e.g., utm_source=google).
• To pass information between pages without requiring server-side storage.
• To apply filters or sort content, like in eCommerce product pages.
• To personalize user experience or remember preferences like selected language or currency.

Because of how versatile they are, query strings have become a key part of modern, interactive web experiences. You’ll find them in everyday SEO tracking, campaign links, and form submissions.

Query strings and SEO

While query strings are useful, they can impact your SEO if not handled properly. Search engines sometimes view different query strings as separate pages, which can cause duplicate content issues. That’s why tools like canonical tags and proper parameter handling in Google Search Console are essential.

It's also important to avoid creating long or confusing URLs with unnecessary query parameters. Clean URLs are easier to share, read, and rank better in search results. For best results, only use query strings when dynamic functionality is necessary.

Differences between query strings and other URL parts

A full URL consists of several parts: the protocol (https), the domain (example.com), the path (/page), and the query string (?search=term). While the domain and path define the location of a page, the query string adds detail about what to display on that page.

Unlike URL paths, query strings don’t change the base structure of the page—they just pass along temporary or optional data. Developers often choose between using path parameters or query strings based on how essential the information is to the resource.

How query strings help personalize website content

Query strings play a behind-the-scenes role in improving website functionality and personalization. For example, an online store might remember your selected size or preferred category using a query string in the URL. They’re also handy in email campaigns, where a unique link with a query string can help identify the exact user who clicked it.

From user experience to analytics, query strings help website owners tailor content and track performance—without requiring users to log in or submit extra data. That’s why they're a simple yet powerful tool for modern blogging, eCommerce, and service-based sites.

FAQs about query string

What does a query string look like?

A query string usually starts with a question mark (?) followed by key-value pairs. For example: ?category=shoes&color=black. Each key (like "category") is matched to a value ("shoes") and separated by an ampersand.

Can query strings affect SEO?

Yes, query strings can sometimes cause duplicate content if different URLs lead to the same page. It's important to manage them correctly using canonical tags or parameter settings in your SEO tools.

Are query strings secure?

Query strings are not secure and should never contain sensitive information like passwords. They're visible in the browser's address bar and can be stored in browser history or server logs.

What’s the difference between a query string and a URL parameter?

They’re often used interchangeably, but technically, URL parameters refer to the key-value pairs within the query string. So, the whole string is the query, while key=value sections are individual parameters.

Can query strings be used for tracking clicks?

Absolutely. Marketing teams often use query strings with UTM parameters to track campaign performance. These help identify where traffic is coming from and what actions users take.

Build smarter websites with less effort

If you're learning about terms like query strings, you're likely thinking about how to improve or build a better website. Whether you’re personalizing content or tracking traffic, tools like query strings are just part of the bigger picture. The good news? You don’t need to be a developer to build a smart, SEO-friendly site. With the B12 AI website builder, you can create a professional site in minutes—no coding required. Sign up today and start building smarter.