Game Maker

Game Maker is a simple to use to that enables the user to create games. You can use drag & drop "commands" and/or the GML programming languages.

All things said about Game Maker apply for both GM8.1(and earlyer) and GM:S (Game Maker: Studio)

Drag & Drop
With Game Makers Drag * Drop functions it is fairly easy for begginers to create a simple game. Most functionality can be achieved using just D&D. There are a few downsides to using this simplistic way of creating games, it makes it harder to find and iron out bugs and if something gets really complex it can become hard to keep track of your code.

GML
GML stands for Game Maker Language, and is the programming language for Game Maker. GML is simmular to Java and allows full control over all of the ability's of Game Maker