What is an algorithm? An ‘in a nutshell’ explanation

An algorithm is the list of instructions and rules that a computer needs to do to complete a task.

Algorithms are in everything we do. But for those that aren’t inclined toward maths and programming, the term ‘algorithm’ is less than clear.

(In fact, the joke runs that developers use the word ‘algorithm’ when they don’t want to explain what they’ve done.)

So, you might have heard the term before, even used it. But what is an algorithm exactly?

What is an algorithm?

In essence, algorithms are simply a series of instructions that are followed, step by step, to do something useful or solve a problem. You could consider a cake recipe an algorithm for making a cake, for example.

In computing, algorithms provide computers with a successive guide to completing actions. They’re comprised of a precise list of instructions that outline exactly how to complete a task.

So, what is an algorithm? A good way to think of them is as mini instruction manuals telling computers how to complete a given task or manipulate given data.

How do computer algorithms work?

Computer algorithms work via input and output. They take the input and apply each step of the algorithm to that information to generate an output.

For example, a search engine is an algorithm that takes a search query as an input and searches its database for items relevant to the words in the query. It then outputs the results.

You can easily visualise algorithms as a flowchart. The input leads to steps and questions that need handling in order. When each section of the flowchart is completed, the generated result is the output.

Algorithms and automation

That sounds straightforward enough so far, but what is an algorithm used for? The truth is decidedly broad.

Algorithms are used throughout all areas of IT and computing. They can manipulate and process data and perform calculations or actions in various ways.

A great example of algorithms in action is with automation software.  This is because automation works by following set rules to complete tasks. Those rules form an algorithm.

So, automation software is made up of many algorithms all working to automate your processes.

For example, one of your automated tasks requires your automation software to take all billing information received by email and put it into a spreadsheet. To do this, you set up a series of rules and conditions for the program to follow — an algorithm.

In this instance, the input is every incoming email. Each of these emails are then put through each step — or rule — to complete the task. This might include scanning each email for key terms. Emails that contain these terms then move to the next step, continuing to follow each step to identify and extract the relevant data. The output is the information that’s placed into a spreadsheet.  


So, what is an algorithm? They’re maps that outline the basic way to do something. In computing, an algorithm is the list of instructions and rules that a computer needs to do to complete a task.

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