According to Andre Walker and many of the hair typing charts, Type 2 Hair is Wavy hair.
Depending on who you talk to, Type 2 hair has a traditional "S" wave pattern with the waves literally looking like a capitol letter S.
The most important characteristic to Type 2 hair which sets it apart from other types is that the waves snuggle into the head and lay mostly flat. Of course S style waves can have some volume and may not be perfectly flat but unlike other types of hair, Type 2 hair has a sleeker profile.
Although most wavy hair tends to be coarse in texture, there are exceptions to the rule and it is possible to have Type 2 wavy hair that has different textures than coarse.
Which is where the Type 2 subcategories come into play.
Type 2A is generally fine and thin.
Type 2B is medium in texture (neither fine nor thick).
Type 2C is thick and most likely to be coarse.
Keep in mind that there is no such thing as "pefect" hair types. Not only can you have multiple types of hair growing on your head at the same time, your hair type might not act exactly like someone else's hair type.
Many people have a combination of Type 1 hair (straight) and Type 2 hair (wavy). Some people with traditional Type 2 hair might have Type 3 (curly) along the nape of the neck or around the hairline.
The reason that different hair typing systems have sprung up over the years is to address the mixture of types.
Although the theory exists that Type 2A hair is the easist to handle with the least amount of frizz (the most common curly hair type), this is not always the case.
While it is much easier to transform curly hair into waves and less easy to transform waves into curls, it can be done with the problem styling products and and tools.