A finite set of rules that gives a sequence of operations for solving a specific type of problem is known as ALGORITHM.
An Algorithm has 5 important features:
1) Finiteness:
An algorithm must always terminate after a finite number of steps.
(A procedure that has all of the characteristics of an algorithm except that it possibly lacks finiteness may be called a computational method.)
2) Definiteness:
Each step of an algorithm must be precisely defined; the actions to be carried out must be rigorously and unambiguously specified for each case.
[An expression of a computational method in a computer language is called a program.]
3) Input:
Quantities that are given to algorithms initially before algorithms begin, or dynamically as the algorithm runs. These inputs are taken from specified sets of objects.
4) Output:
Quantities that have a specified relation to the inputs.
5) Effectiveness:
Algorithm operation must all be sufficiently basic that they can in principle be done exactly and in a finite length of time by someone using pencil and paper.
Bibliography: The Art of Computer Programming: Donald E. Knuth