TL;DR
There are two types of penalties that can be given by Google: manual and algorithmic.
The algorithmic penalty may affect website rankings after an update to the Google algorithm.
Previous major updates like Panda and Penguin have been at the root of algorithmic penalties for websites who do not comply with webmaster guidelines. This type of penalty can not be reconsidered by Google and websites need to fix the issues they believe caused the penalty.
What is an Algorithmic Penalty?
If you notice your website is going through major drops in rankings on the Google SERP, it may be caused by two types of issues:
- A manual penalty from a Google employee who has found your website in violation of the Google recommended policies for webmasters.
- An algorithmic penalty not aimed specifically at your website, but at a certain common practice that may not be in compliance with Google webmaster guidelines.
You can easily differentiate between the two, as a manual penalty will be displayed in your Google Search Console account, in the “Security and Manual Actions” menu. If there is no mention of a penalty here, then the cause for your significant drop in rankings must be an algorithmic penalty.