They allow the measurement of the activity of the website in order to make statistics of its use, traffic and also, to introduce improvements based on the analysis of the use data made by the users of the service.
They allow the management of the advertising spaces included on the web.
They allow navigation through a web page, platform or application and the use of the different options or services that exist in it (eg: control data traffic, identify the session, remember the elements of an order).