Gclid stands for Google Click Identifier. This parameter uses in Google Adwords. Google uses this to track the Adword click and their conversion using Google Analytic.

So gclid is just a parameter which uses with Google Analytic. It’s encoded value. In gclid google store the click time and adwords data which uses in Google Adwords Report.

So gclid is auto-tagging parameter, which is encoded with hash value and that map back to a specific AdWords.

This will be something like this:

http://nitinmaurya.com/?gclid=Cj0KCQiA-ebSBRC8ARIsAGuxJIq2hpBhNJAHovjIUvkZqXT8cbWWJ2WTpB2i-EEVTd9hORkjBqCV65waAup6EALw_wcB

gclid can contains the following values:

• Campaign like UTM Source, keywords etc.
• AdGroup
• Search Query and many more..