Introduction to Algorithms



What is an algorithm?

An algorithm is a set of step-by-step instructions used to solve a problem. They are used by both human beings and computers.

Algorithms for Humans

Common examples of algorithms for humans include:


Fire evacuation Procuedures

Fire evacuation Procedures

Cooking Recipes

Cooking Recipes

Furniture assembly instructions

Furniture assembly instructions

Washing Machine Usage Instrucitons

Washing Machine Usage Instrucitons

Algorithms for Computers

Computers require algorithms to function and these usually come in the form of software. Computers differ from humans in that the instructions provided must completely unambiguous – they must be clear and not open to interpretation.

Algorithms for computers include:

  • Software program instructions
  • Device handling instructions
  • Data storage instructions
BBC Bitesize Video – What is an algorithm?

Activity 1

Activity 1 – Alien shopping algorithm

An alien has landed on earth and you have decided to send him on an important mission โ€“ to do your weekly shopping down at the supermarket! You have been given a shopping list. The alien has never been shopping before โ€“ can you write a set of instructions for it to do the shopping for you?


Your algorithm must be:

  • Step-by-step.
  • Unambiguous โ€“ Each step must be completely clear and specific.