There are some pretty serious restrictions on what you can store in cookies, mostly established by the original specification:
Only simple strings can be stored. Because dates and numbers can be expressed as strings, you can store them as cookies. But no ColdFusion-specific data types, such as arrays and structures, can be specified as the value for a cookie.
A maximum of 20 cookies can be set within any one domain. This prevents cookies from eventually taking up a lot of hard drive space. Browsers might or might not choose to enforce this limit.
A cookie can be only 4 KB long. The name of the cookie is considered part of its length.
The browser isn’t obligated to store more than 300 cookies. (That is 300 total, counting all ...