The Media Library allows for up to 128 categories. Items can be assigned to any category and/or combination of categories. Therefore, you are not limited to having each item in just a single category, as you are with most other systems.
You use categories as flags, indicators, and to help manage your library in general. In many cases you will use categories as genres, and will have categories such as "rock", "pop", "dance", etc. You may also have categories such as "1960s", "1970s", etc. These types of categories make finding specific music very easy and fast. OtsAV can automatically create and assign these types of categories based on the Genre and Release information stored within your Ots Album files.
Categories are also useful as other types of flags. For example, you may have a category called "explicit", in which you place all items which contain lyrics of an explicit nature. Then, while in an environment where these types of lyrics would not be appropriate, you could easily filter out any items which are within the "explicit" category.
It is also common to have a category of personal favorites, and if you're a DJ, a category called "mustplay", in which you assign all items which you know from experience go down really well at a gig.
Categories can also be useful as temporary markers. For example, you may have a category that you use to indicate that you have fully processed the underlying Ots file (checked and set perfect ACI mixing points, ensured title/artist info is 100% correct, etc), and as you do this to each album, you assign its items into this special category. Then, you can easily see at a glance which items still require this process to be done.
In short, categories are a pivotal part of the Media Library system, and you will find increasing potential in OtsAV as a tool, the more you embrace categories and OMQL which leverages upon them.
For examples of querying the Media Library using OMQL click here.
How to display categories in Media Library area
Managing the Media Library categories