All the webs of last generation used cookis and pursuant to Royal Decree-Law 13/2012 inform you of this.
A cookie (or computer cookie) is a small piece of information sent by a website and stored in the user´s browser so that the website can view previous user activity.
Its main functions are:
Keeping track of users: When a user enters their username and password, a cookie is stored so you do not have to be introducing them to each page server. However, a cookie does not identify only one person, but to a combination of computer-browser-user.
Getting information about the user´s browsing habits, and attempted spyware (spyware), by advertising agencies and others. This may cause privacy and is one of the reasons why the cookies have their detractors.
Cookies can be deleted, accepted or blocked as desired, so this should only be conveniently configure the web browser.