Basics

Let's start with the basics : Apps

An App is either a Game or a DLC
When we talk about Apps, it could refer to either one.

All the statistics are about Released apps. Upcoming apps will have their own statistics.

Games and DLCs

On the Store, you'll find NaN Apps :

Games
DLCs

Games and DLCs are almost identical

They have their own price, release date, even reviews.

The key difference is that DLCs don't have Achievements.
That's the reason why you'll see people complaining about not being able to 100% a game without buying the DLCs :
The DLCs achievements are all in the game itself.

Games maturity

Every App can have multiple Content type, I usually call it Maturity.

As a Steam user, you can choose how the apps are filtered :
Steam account preferences

To break it down, you'll find 5 Content types :

General Mature - Heavily involves topics like war, death, etc
Frequent Violence or Gore - It doesn't have to be graphic
Some Nudity or Sexuality - Suggestive scenes are enough
Frequent Nudity or Sexuality - It's not about it but...
Adult Only or Sexuality - Straight up porn

Let's call then Mature, Violent, Nudity, Sexual and Porn.

If you don't have an account, you can't find or browse Sexual and Porn apps

If the app falls into none of those types, we'll call it Vanilla