what are persistant cookies? How long do they exist?

Question

I heard cookies are stored in my browser. But what are persistant cookies? Where they are stored? What is the use of those cookies?

Answer 1

A persistent cookie is one that remains on your machine past the point of session expiration. It is stored on disk, and used for websites to remember you (or other information about you, or other information it deems necessary to store) between visits. For example, this is how Amazon knows who you are even if you shut down your machine and come back another time.

These are the cookies that get removed when you access your browser's preferences and select the "delete cookies" option.

Usually persistent cookies are created by setting an expiration date on the cookie, so that the browser doesn't remove it at the end of the session by default.

Also, it's not quite right to say that cookies are stored "in the browser". A browser is just a running application, which may load cookie data into memory when it needs to. All cookies are stored in the same space; what makes a cookie persistent is just whether it gets removed when your session is over.

Answer 2

Persistent cookies are stored in your webbrowser once you closed it. It can be used to track users or just to let them stay signed in (as may know from many webapplications). Those are stored as long as a webpage choose to (Google even used to set that date 30 years in advance!). If the website doesn't set an expiration time it is deleted once the browser is closed. You may also delete the cookies manually using the browser menu.

The Adobe Flash player has it's own machanism called LSO. These are hard to delete. You may use an Adobe tool for that. Such cookies are mostly used to track users cross-site for advertising reasons.

Answer 3

Cookies are basically used so a website can keep track of who you are. There are many different reasons why a website may need to know who you are.

For example if you are visiting a website with a shopping cart it needs to know who you are so it can keep track of the items you have added to your card. When you login to a website and see an option that says "remember me" the website is placing a persistent cookie on your computer so you don't have to type your username and password every time you visit the site.

Each web browser stores cookies in a different places. A cookie is just a simple text file that contains information about what website sent the cookie and what information was in that cookie (usually just a unique id number).