1. Since cookies are used to record information about your activities on a particular domain, they can only be read by the domain that created them

2. A single domain cannot set more than twenty cookies, and each cookie is limited to a maximum size of 4 KB

3. A cookie usually possesses six attributes, of which only the first is mandatory. Here they are:
* name: the name of the cookie
* value: the value of the cookie
* expires: the date and time at which the cookie expires
* path: the top-level directory on the domain from which cookie data can be accessed
* domain: the domain for which the cookie is valid
* secure: a Boolean flag indicating whether the cookie should be transmitted only over a secure HTTP connection

It's important to remember that, since cookies are stored on the user's hard drive, you as the developer have very little control over them. If a user decides to turn off cookie support in his or her browser, your cookies will simply not be saved. Therefore, avoid writing code that depends heavily on cookies; and have a backup plan ready in case cookie data cannot be retrieved from the client.

Two types of cookies