Browsers

A web browser is an Eierlegende Wollmilchsau It is the single, central point of human digital activity. Some browsers are only slightly smaller and less complex than an operating system.

To a good approximation there are two. One is effectively owned by Google the other by Apple. Browsers depend on "web rendering engines", of which there are a few. Microsoft's browser is built from the same engine as Google's, and Mozilla's.

A browser is the single main security weakness in any information system. The greater its complexity the less secure it is. Since features drive popularity and features increase complexity, the least secure browsers are the most common. As a damage multiplier, because they are more popular they are the most attacked, since attackers play the numbers game.

Your choice, use and maintenance of your browser is the third most powerful security leverage point you have.