What is Chromium?

Chromium is a web browser developed by Google. Many modern web browsers use its codebase and extend upon it, for example:

Why is this a bad thing?

Chromium based browsers dominate the market. This means that any changes Google makes to the Chromium code base are also present in the browsers that build on it. As Chromium based browsers are the majority, websites have to adapt. This also forces non chromium browsers like Firefox to implement these changes. This gives Google the power to steer the web in a direction they benefit from the most.

Examples

What can I do

You should use alternative browsers like Firefox or, even better, LibreWolf