What is a Cookie – Part 2
Part 1 of this series discussed some of the differences between how analytics packages work. Some of the most popular web analytics systems (Google Analytics, Omniture to name a couple) use Javascript which takes advantage of cookies. Part 1 covered most of this except for the difference between cookies.
There are 4 types of cookies that fall into two categories.
- First Party Cookies
- Third Party Cookies
- Persistent Cookies
- Temporary Cookies
First Party vs. Third Party Cookies
“Back in the day” analytics providers used third-party cookies which meant, when you visited a site, www.analyticscookies.com for example, the cookie was sent from the vendor – www.omniture.com for example. These third-party cookies handled visitors who navigated across multiple, unrelated domains within a companies site. Due to issues around privacy and issues around some companies using third-party cookies to provide personal information, users began to block third-party cookies. Most analytics vendors have now switched to first-party cookies.
A first-party cookie is now primarily used because web users tend to delete or reject them less frequently. As a result, they do a very good job of tracking repeat visitors. In fact, some sites like gmail won’t work unless you accept first party cookies.
Persistent vs. Temporary Cookies
A temporary cookie (also called transient or session cookie) is used to track a users session. When a user visits a site, performs some actions (clicks, navigates, perhaps fills out a form) these are tracked as a session. The cookie is set when you visit a site and deleted when you leave – hence the name “temporary”
A persistent cookie is set when a user visits a website for the first time. It will remain on a users computer for the duration that the website determines – more often than not, about 18 months. Persistent cookies remain until a users either deletes the cookie. If and when the cookies is deleted, and a user returns to the same website, the analytics package would define this second visit as a “new visit.” This, along with many other reasons are why analytics systems are never “perfect” and any good web analytics consultant should educate their clients of the limitations of some systems.
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