BBTag feature five different types of variables, each with a different scope. These types are distinguished from each other with prefixes. These variables can be used for numerous operations and functions.
All the other variable types are immediately stored to a database for data persistence. Temporary variables, however, do not. As such, they are faster and have the smallest scope. Use these variables if you don't need to reuse them between executions.
Local VariablesPrefix: none
Local variables are your classic variables. They are unique per-tag, and not shared by anything.
Unlike local variables, guild variables are unique per-guild (server). They are intended for allowing separate tags to communicate with each other and other tags on the same guild.
Additionally, there are actually two separate pools of guild variables - one for tags, and another for custom commands. This means that public tags don't share the same variables as custom commands, even on the same guild.
Author variables are similar to guild variables, in that they allow tags to communicate with each other. However, they are unique per-author. This means that it is a set of variables that only you can ever touch. Other than global variables, author variables are the only type that allow for tags and custom commands to communicate.
These variables are in a public pool, meaning that anybody is able to access or modify them. As a general rule of thumb, if you don't want somebody using your variables, don't use global ones!