Wondering who creates the category names? You do. You create each category name and choose the color that's associated with it. Then, you can assign that category to incoming and existing messages. One way to assign a color category to a message is to right-click in the Categories column and use the shortcut menu, as we've shown in the picture.
Once you've assigned a category to a message, you can quickly scan your Inbox and find the message just by looking for its colored tag.
Tip Unless you're adapting an existing system that's already working for you, it's probably best to stick to just a few categories. Keeping the system simple will make it easier to use.