Basically, an algorithm is a sequence of instructions that is designed to solve a problem. It can be used in computer science for a wide variety of tasks. It is a logical procedure that provides results in a finite time. It is usually written in a step-by-step fashion.

Besides mathematical problems, algorithms are used in day-to-day life. They can be used in data processing, automated reasoning, and other areas. They are written in a programming language and are normally independent of the underlying programming code.

An algorithm should have clear directions and well-defined outputs. It should also be easy to understand and implement. It should not contain anything subjective. It should be extensible and not limitless. It should be efficient and use the available resources.

An algorithm can be divided into four different types: recursive, backtracking, dynamic, and best first. Each of these types is efficient in different ways.

A recursive algorithm is a technique that works to solve problems by breaking them down into smaller subproblems. It remembers past results and uses them to create a new solution. The best-first method finds the best choice on each iteration. It also takes less time.

A dynamic programming algorithm breaks a complex problem into smaller and simpler subproblems. Then it combines these subproblems into a final answer. It also stores the result for future use. It is similar to the memoization technique.

A best-first algorithm divides a problem into smaller subproblems and then computes a complex program. This is a popular technique in machine learning. It works by grouping items into categories based on pre-categorized training data.