# Algorithms ## What's an algorithm? > An algorithm is simply a series of logical instructions that show, from start to finish, how to accomplish a task. By this broad definition, a cake recipe counts as an algorithm. > > – [[Hello World]] > Usually, algorithms refer to something a little more specific. They still boil down to a list of step-by-step instructions, but these algorithms are almost always mathematical objects. > > – [[Hello World]] ## Types of algorithm There's no overall consensus on how to group algorithms, but you can think of four main categories ([[Hello World]]): - [[prioritization]] (making an ordered list) - [[classification]] (picking a category) - [[association]] (finding links) - [[filtering]] (isolating what's important) Most algorithms are some combination of the above. ## Algorithmic approaches You can think of the approaches taken by algorithms as broadly fitting into two key paradigms. - [[Rule-based algorithms]] - [[Machine-learning algorithms]]