LIGO is strongly and statically typed. This means that the compiler checks how your contract processes data, ensuring that each function's expectations are met. If it passes the test, your contract will not fail at run-time due to some inconsistent assumptions on your data. This is called type checking.
LIGO types are built on top of Michelson's type system.
For quick reference, you can find all the built-in types here.
Type aliasing consists of renaming a given type when the context calls for a more precise name. This increases readability and maintainability of your smart contracts. For example we can choose to alias a string type as an animal breed - this will allow us to communicate our intent with added clarity.
The above type definitions are aliases, which means that
stringare interchangeable in all contexts.