Game Maker Language

Game Maker Language (GML) is a scripting language developed for use with a computer game creation application called Game Maker. It was originally created by Mark Overmars to supplement the drag-and-drop action system used in Game Maker. However, in the latest versions, all the drag-and-drop actions translate to GML rather than being separate from it.
GML is heavily integrated with the Game Maker environment. Usually, elements such as sprites and sounds are all organized within the Game Maker IDE (though they can also be loaded from external files). Game Maker's architecture is designed to handle such things as event detection, level design, and object configuration without the need to code them manually, minimizing code verbosity with intuitive interface features.
A common misconception is that languages such as Pascal and C++ can be directly used in GML. This is incorrect, and is a common mistake due to GML's ability to utilise Pascal and C++ style syntax (e.g. "&&" is interchangeable with "and").

Libraries
In Game Maker, a set of drag-and-drop actions is called a library. In the Game Maker interface, these libraries are displayed as tabs containing icons called actions. Each action is a GML script or function that users can use in their games. Game Maker comes with a default set of libraries that contain the common actions used by most games; it is also possible to create libraries using the Library builder provided separately from Game Maker. There are many libraries that a Game Maker user may download to avoid using GML to achieve certain tasks. For example: If a user wants to make a simple 3D game but has no experience with GML, they can download a 3D Library.

GML syntax and semantics
GML is structurally similar to C-based languages in its use of code blocks, function calls, variable assignments, operator syntax, and so on.
GML makes a difference between statements and expressions. For example g < 1; is not a valid statement and GM will return an error. Also, variable assignment is always a statement in GM, and cannot be used in an expression.