[ al-guh-rith-uhm ]
/ ˈæl gəˌrɪð əm /
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See synonyms for: algorithm / algorithmic on Thesaurus.com

Mathematics. a set of rules for solving a problem in a finite number of steps, as the Euclidean algorithm for finding the greatest common divisor.
Computers. an ordered set of instructions recursively applied to transform data input into processed data output, as a mathematical solution, descriptive statistics, internet search engine result, or predictive text suggestions.
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Origin of algorithm

First recorded in 1690–1700; variant of algorism, by association with Greek arithmós “number”; see arithmetic


al·go·rith·mic, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


What is an algorithm?

An algorithm is a set of instructions or rules that can be followed to solve a problem.

Algorithms are most commonly used in mathematics and computing, and they can often be very complex or have many steps or sets of instructions.

For example, your teacher asks you to add 537 and 162. You might solve the problem by lining up 162 under 537 and adding the columns of numbers together. You add the 7 and 2 in the ones column to get 9, Next, you add the numbers in the tens column (3 and 6) to get 9. Finally, you add 5 and 1 in the hundreds column and get 6. Your answer, then, is 699. You have followed an addition algorithm to find the solution.

In computing, a computer coder will create a set of instructions (the algorithm) that a computer or artificial intelligence will use to solve a problem or will consult in order to achieve a goal. Let’s say you spend the day watching Star Wars videos on YouTube. With each video you watch, the website will recommend other videos it thinks you will like. How does it know what you like? It runs an algorithm that finds videos that are similar to the ones you’ve already watched. If Darth Vader shows up in a video of a car commercial, YouTube will likely recommend it to you to watch because Vader was in a lot of the Star Wars videos you’ve already watched.

Why is algorithm important?

The first records of the term algorithm come from around 1690. It is a variation of the older word algorism, which ultimately comes from the name of the ninth-century mathematician Muhammad ibn Musa al-Khwarizmi. Actual algorithms have been used in math since ancient times. The Euclidean algorithm, for example, was thought up by the Greek mathematician Euclid around 300 b.c.e.

Just by using the internet, you have very likely run into an algorithm—or at least the results of one. Search engines use algorithms to figure out what order to put search results in, websites use them to determine which ads to show you, and social media websites use them to decide which of your friends’ posts you are most likely to want to see.

Many websites keep the specifics of how their algorithm works a secret. They do this in order to prevent users from exploiting or abusing the algorithm to guarantee it selects their content over everyone else’s. For example, if a user knew that YouTube’s recommendation algorithm prioritizes videos that are exactly four minutes long, they could create hundreds of four-minute videos to trick the algorithm into showing their videos to the majority of YouTube users.

Did you know … ?

Many algorithms used on websites are designed to adjust themselves and learn the best ways to accomplish problems. Because of this, algorithms will often behave in ways their designers never expected. An algorithm can even change itself to the point that even the original creator has no idea how it works anymore.

What are real-life examples of algorithm?

This video gives a simplified explanation of how computing algorithms work:

Many people have become familiar (and annoyed) with algorithms, thanks to their increasingly common use in computing.


What other words are related to algorithm?

Quiz yourself!

Is the following a correct use of algorithm?

Rather than follow a set of instructions, the website instead uses an algorithm that randomly selects which advertisements to show users.

How to use algorithm in a sentence

British Dictionary definitions for algorithm

/ (ˈælɡəˌrɪðəm) /

a logical arithmetical or computational procedure that if correctly applied ensures the solution of a problemCompare heuristic
logic maths a recursive procedure whereby an infinite sequence of terms can be generated
French name: algorism

Derived forms of algorithm

algorithmic, adjectivealgorithmically, adverb

Word Origin for algorithm

C17: changed from algorism, through influence of Greek arithmos number
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for algorithm

[ ălgə-rĭð′əm ]

A finite set of unambiguous instructions performed in a prescribed sequence to achieve a goal, especially a mathematical rule or procedure used to compute a desired result. Algorithms are the basis for most computer programming.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for algorithm

[ (al-guh-rith-uhm) ]

A set of instructions for solving a problem, especially on a computer. An algorithm for finding your total grocery bill, for example, would direct you to add up the costs of individual items to find the total.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.