Data type
- A data type in a programming language is a characteristic that defines the nature of the value that a data element has
Type checking
- A system of checking if values has been assigned their correct types
- Essential in programming to minimize errors during the execution of programs
- Every programming language has this
- Usually occurs at either runtime or compile time
- The two main ways of type checking in most languages are static and dynamic
Diagram

Dynamically Typed

Overview

A language is dynamically typed if the type is associated with run-time values, and not named variables/fields/etc

You don’t declare variable types explicitly, but the type is inferred at runtime based on the assigned value.
- Variables are checked against types only when the program is executing!
- Python, JavaScript
Characteristics
- No requirement to explicitly state the data type during variable declarations, since the language system can detect the type of variable at runtime
  - The computer decides, so efficiency is low
- Altering the data type of previously declared variables is allowed
Convenience and readability - easier to understand

Statically Typed

Overview

A language is statically typed if the type of a variable is known at compile time.

You explicitly declare variable types, or the compiler infers them at compile time.
- Compile time is when a specific programming language is converted to a machine-readable format
- This means that before source code is compiled, the type associated with each and every single variable must be known
- ☕Java, C++
Characteristics
- Detection of errors in variable-data type associations will halt the compilation process until error is fixed!
- A variable declared with a specific data type cannot be assigned to another later
Detailedness, lots of safety devices, prevents mistakes

Feature	Dynamic	Static
Type Checking	At runtime	At compile time
Variable types	Determined when code runs	Declared before running
Flexibility	More flexible, less boilerplate	Stricter, but safer
Errors	May fail at runtime (type errors)	Type errors caught early (before running)
Performance	Usually slower	Usually faster
Scope	Better for fast, small personal projects	Better for big projects that needs lots of collaboration
Examples	Python, JavaScript	C++, ☕Java