Algorithm

An algorithm is a finite, ordered sequence of unambiguously defined steps that leads to the solution of a specific problem or the completion of a task. It can be compared to a precise recipe: for given input, an algorithm describes which operations to perform and in what order to obtain the expected result.

How an algorithm works

A good algorithm should meet several traits: it must be finite (end after a defined number of steps), unambiguous (each step interpreted the same way), correct (give the right result for valid input), and efficient (use time and memory reasonably). The same problem can be solved by different algorithms that vary in complexity — which is why, with large datasets, choosing the right algorithm determines the performance of the whole system.

Algorithms are the foundation of computer science: sorting, searching, encryption, and data compression are all sets of well-defined algorithms. Increasingly, algorithms are not written out explicitly but derived from data through machine learning and artificial intelligence.

Algorithms in practice

In the context of websites and marketing, people most often talk about search engine algorithms. They decide the order in which results appear for a query, judging pages by hundreds of ranking factors. The Googlebot crawler gathers data about pages, and ranking algorithms order them in the results. Understanding how these algorithms work is the essence of SEO; their updates can significantly shift a site's visibility, and violating the guidelines may lead to a Google penalty. Algorithms also run inside servers and web apps, deciding request order, load balancing, data compression, and connection encryption, which directly affects a site's speed and hosting costs.