Google has a list of Webmaster Guidelines that outline its expectations for creating webpages that serve users rather than simply try to decode the algorithm.
Google will levy a punishment on sites where content is deemed to be in conflict with these guidelines. If a site receives a penalty, it means that Google has determined some aspect of the guidelines has been violated.
Violations can result from a variety of factors, including:
- Unnatural links that Google believes you are manipulating without the user’s best interest in mind
- A website that has been hacked
- Content that adds little or no value
It’s important to perform site audits periodically to check your SERP position and see if Google has penalized you.