How to distinguish an imperative programming language from a declarative one and what are their main differences?

An imperative programming language describes how a task should be performed — step by step, with specific commands and changes in state. Example: loops, assignments, flow control.

A declarative language describes what needs to be achieved, without specifying the exact steps to perform. It focuses on describing the result or logic.

Main differences:

• Imperative: control of the process, changing state, sequence of operations.
• Declarative: describing the desired result without explicit flow control.

Example:

Imperative (in Python):

result = []
for i in range(10):
    if i % 2 == 0:
        result.append(i)

Declarative (in SQL):

SELECT number FROM numbers WHERE number % 2 = 0;