Google penalty
A Google penalty is a punishment Google hands out for breaking its webmaster guidelines (now called Google Search Essentials). Once you have a penalty, your site is practically impossible to find in the search results, and your visitor numbers usually drop sharply.
How do you get a Google penalty?
You get a penalty by not following Google's guidelines. For example, by using black hat SEO techniques such as cloaking or hidden text. But a site with many low-quality pages, often combined with lots of ads, can also get a penalty.
Manual or automatic penalty
There are two kinds of Google penalties. With a manual penalty, someone at Google has penalized your site by hand. Automatic penalties are far more common: Google's algorithm has found that your site does not follow the guidelines.
Fixing a Google penalty
If you have a Google penalty, or suspect you do, fix it as soon as possible. Otherwise you lose a lot of visitors and revenue.
Start in Google Search Console. If you have a manual penalty, you will always find a message about it there. A manual penalty is only given for serious violations, so fixing it takes real effort: expect to make substantial changes to your site.
An algorithmic penalty is harder to spot. The sign is a sudden or gradual drop in visitors that you cannot explain by anything outside your site. You fix an automatic penalty by taking a hard look at the quality of your site. Need help with that? Have a look at KRL Media