A type defines not just the possible values that some data can take, but also the operations which can be performed on that data.
For example, the int type represents integers, and supports arithmetic operations, bitwise operations and comparison operations.
Computer programs use variables and data structures to store data in memory.(1) A data structure is a scheme for representing values of some type in memory; before we can understand, analyse and design data structures, we need to understand memory.
Programmers deal with many types of data: most programming languages have integers, booleans, floating point numbers, strings, lists, and more.
The word “type” has a specific meaning: each value has a type.
In Python the value 1 has the type int, and the value 'Hello, world!' has the type str.
In Java the value 1 has the type int, and the value "Hello, world!" has the type String.