All About Cookies

There are two different types of cookies: session cookies and persistent cookies. A cookie without an expiration date and time is considered as a session cookie by the web browser.

Session cookies, also known as in-memory cookies, transient cookies, non-persistent cookies or temporary cookies are stored in computer memory accessed only by the browser and are never written to disk as a cookie file. Once the browser is closed - all the session cookies are permanently removed.

When a browser sends a request to a website to load a page, the response from the server contains the set-cookie response header containing a key-value pair (in our example on the screenshot below the key is session_cookie_sample and the value is allaboutcookies.info).

Browser takes that key-value pair and stores it as a cookie, but as the expiry was not set - the browser saves this cookie into a memory. Still, you can find this cookie within the browser and it looks like this (at least in Chrome or Chromium based browsers):

The Expires field is not set and it states that the cookie will be removed when the browser session ends.