URL, short for Uniform Resource Locator, is web address that you see on web browsers.
You may have seen urls that look something like this.
The part after the question mark is a query string. It appears at the end of a URL and provides a way to send additional information that a web server can use to control the output of its response.
Generally a query string is used to search a database for information, and return a single record.
For example, if you want to send a link to a youtube video but you wish to start the video at a particular time you can forward the link as such:
Where v=iAJhtHDwcS4 after the question mark identifies which video to show from the youtube server and t=39m29s after # is the minutes and seconds the video will start from. The character # is used here to further specify a subsection (or fragment) of the video.
Query strings can hold multiple value pairs. Simply add an ampersand, followed by another name, an equal sign and another value.
There are some requirements for query strings. Most importantly, you can’t just use any symbol you want in a query string. Some characters like the ampersand(&), equal(=), space( ), and quote marks(“”) have special meaning in a URL. So if you send information that includes those special characters you need to encode them. That is, translate them into a set of symbols that are safe and don’t conflict with their URL specific version. For example, ampersand is represented by “%26”. A space is converted to a plus(+). And a plus is converted to “%2B”.
URL encode and decode is a website that can decode url query string symbols in case you are curious: http://www.url-encode-decode.com/