: There's a list of limits put on cookies:
- Cookies are limited to one domain. There is a limit of 20 cookies per domain. Cookies can be read only from pages from that domain.
- Cookies can further be limited by paths, so that only pages with a specific path on that domain may read the cookie.
- Cookies have an expiry date. If no such date is set, they will only survive as long as the browser session is still running.
- Cookies that pass the expiry date are removed, but not necessarily from your harddrive. It depends on how your browser stores them.
- Cookies may be 4kb long each, name of the cookie included.
- Your max limit is no smaller than 300 cookies in total.
- Most browsers allow no longer expiry time than three years. Some have a 90 day limit even.
Official specifications exist for this, and can be found at Netscape Cookie Specification
, which is the base for the IETF RFC2109