What is a data type?

• A classification identifying a type of data.
• Each data type specifies what kind of data is stored within it.

Built-in data types

• In most programming languages, there is a set of built-in data types. The built-in data types for Python that we commonly use are:
  • int — used for integer numbers
  • float — used for decimal (or floating point) numbers
  • str — used for strings (a sequence of characters)
  • bool — used to hold either True or False (boolean)
  • list — used to store multiple values of other data types in an ordered sequence
  • set — used to store multiple values of other data types in an unordered sequence
  • dict — used to store information in key-value pair (dictionary)

• An immutable data type is a type of a variable (or an object) whose value cannot be changed after its creation.
• int, float, and str are immutable data types
• A variable with this type can be reassigned but a reference from a variable is going to point to somewhere else in memory.

• A mutable data type is a type of a variable (or an object) whose value can be changed after its creation.
• list, set, and dict are mutable data type.
• A variable with this type can be reassigned. A reference from a variable still points the same place in memory