What is a social media algorithm?

Many founders post content on social media and find their reach is inconsistent — sometimes a post is seen by thousands, other times by almost none. The variable governing this is the platform algorithm: a set of rules each platform uses to decide what content to show to which users. Understanding how algorithms work at a structural level helps founders create content more likely to be surfaced.

A social media algorithm is the system a platform uses to decide which content to show in each user's feed, in what order, and how widely to distribute it beyond existing followers. Algorithms typically prioritise content that generates early engagement — likes, comments, shares, and saves — as signals that the content is worth showing to more people. They also favour content matching the preferences of individual users and, in some cases, formats the platform is currently promoting.

Algorithm behaviour changes over time and varies significantly between platforms — treating any specific tactic as a permanent solution is a mistake. The most durable approach is creating content that generates genuine engagement from a relevant audience, which is what all platform algorithms are ultimately designed to surface. Our guide to social media algorithms covers the key principles and how UK founders can work with them rather than against them.