Why does Google Analytics use __utm.gif?

Question

Just trying to understand why they didn\'t use a REST API.

Answer 1

Because it's an image you can stick it anywhere you can use and image tag even if you can't execute JS. Many years back this Google pushed this for tracking of email campaigns. You could stick this formatted string in an html email message and then any client that displays the message will send that request to the GA servers and you will get at a minimum IP info (which get's you geo location also) depending on client you may also get OS, language and all the other browser settings. You don't get all the fancy analytics you get from the modern JS tracking scripts but if still has it's uses.

Here is a site that will help you format the request string and also has some more details. Google pixel generator