In the ninth century, Abu Abdullah Muhammad ibn Musa al-Khwarizmi, a Persian mathematician, introduced algebraic concepts and Arabic numerals while working in Baghdad, which was then an international center for scientific study. His method for performing arithmetic with Arabic numerals was called algorism. By the eighteenth century, the term had evolved into algorithm. Algorithms are finite sets of carefully defined instructions. They are procedures used to accomplish a task and reach a defined end-state. Algorithms are used in linguistics, computers, and mathematics.
Many people think of algorithms as steps in a well-written recipe. If you follow each step of the recipe exactly, you should end up with an edible dinner. In the same way, if you follow each step of an algorithm, you should arrive at the proper solution. Simple algorithms can also be used to design more complex algorithms.
Computers use algorithms to process information. All computer programs are created with algorithms, or series of algorithms, that give the computer instructions to follow. When using an algorithm to process information, computers usually read data from an input device. For an algorithm to work successfully, it must be carefully defined so a computer can read it. Program designers need to consider every possible scenario that could arise and create a series of algorithms to resolve the problem.
Designers must also be careful not to change the order of the instructions, because computers cannot cope with an algorithm that is in the wrong place. Flow of control refers to the way a list of algorithms must begin at the top and continue to the bottom, following every step along the way.
Some terms used to describe algorithms include natural languages, flowcharts, pseudocode, and programming languages. Natural expression algorithms are generally seen only in simple algorithms. Computers usually use programming languages that are designed for expressing algorithms.
There are several ways to classify algorithms. One method is by the specific type of algorithm. Types of algorithms include recursive and iterative algorithms, deterministic and non-deterministic algorithms, and approximation algorithms. Another method is by design methodology or paradigm. Common paradigms include divide and conquer, the greedy method, linear programming, dynamic programming, search and enumeration, reduction, and probabilistic and heuristic paradigms.
Different fields of scientific study classify algorithms in different ways, usually to make work in that field as efficient as possible. Some types of algorithms used across scientific fields include search algorithms, merge algorithms, string algorithms, combinatorial algorithms, cryptography, sorting algorithms, numerical algorithms, graph algorithms, computational geometric algorithms, data compression algorithms, and parsing techniques.
Internet search engines use algorithms to aid in search engine optimization. Google’s web crawlers use a link analysis algorithm to index and rank web pages. To prevent webmasters from using underhanded schemes to influence search engine optimization, many internet search engines disclose very little about the algorithms they use in their search engine optimization techniques.
