1 They are not programs
Internet cookies are not programs or executable files. Thus they can never cause damage to a computer. A cookie file is a simple file that stores information on your own PC.
2 Cookies don't store personal information
Cookies don't store personal information such as name, email or phone number. Instead, they are mainly used to help you browse sites. Some cookies are used by advertisers to display tailored ads to a PC based on the cookies stored on it. This is why some people think that cookies invade privacy.
3 They only collect the data you provide
Cookies don't collect data on their own. They just store the data you provide them with. If, for example, you visit a certain site then a stored cookie on your PC will have a link to that site. Later on, another site can use that cookie to show you tailored ads based on that site you visited.
4 They are not permanent
Most cookies have expiration dates. And even if a cookie doesn't remove itself, deleting cookies is usually an easy task that most browsers handle well.
5 Cookies can't be used to identify you
Cookies can't be used to identify you as a person. The only thing they can do is connect a certain IP address with certain browsing habits. Cookies collect information about you as an anonymous user, for they can't get your real identity.
6 They are not spyware
Cookies are no more than text files. Thus they can't contain spamware, spyware and they can't affect the behavior of any program on your computer. (See Why do people fall victim to scams?)
7 Login cookies aren't shared with other sites
If a site creates a cookie on your PC to keep you logged in to your account, for example, then this cookie is never shared except with the site that created it, so no one will be able to know about your login information.