What is complexity?🤔🤔And how to determine it for any algorithm?

Question

define all things related complexity

Answer 1

The number of (machine) instructions which a program executes during its running time is called its time complexity in computer science. This number depends primarily on the size of the program's input, that is approximately on the number of the strings to be sorted (and their length) and the algorithm used.

it's of 2 types time & space complexity
time complexity :-The number of (machine) instructions which a program executes during its running time is called its time complexity in computer science

space complexity :- This is essentially the number of memory cells which an algorithm needs. A good algorithm keeps this number as small as possible, too.