The default browser stylesheet is the set of rules that browser have to apply some minimum style to elements.

Most of the times those styles are very useful.

Since every browser has its own set, it's common finding a common ground.

Rather than removing all defaults, like one of the CSS reset approaches do, the normalizing process removes browser inconsistencies, while keeping a basic set of rules you can rely on.

Normalize is the most commonly used solution for this problem.

You must load the normalizing CSS file before any other CSS.