There are two types of Google penalty. Manual penalty and algorithmic penalty. Both penalties find through different ways.

Manual penalty: To find manual penalty, go to your site search console and check under SECURITY & MANUAL ACTIONS / MANUAL ACTIONS. If you get no issue detect, then there is no manual penalty hit on your site.

Algorithmic Penalty: To find algorithmic penalty check your google analytic and see if there is any significant drop in traffic after google latest update. If there is any, then it’s a signal of google penalty.

Suppose there is a significant drop in traffic after any google latest update and even after producing quality content, your site is not ranking. In that case, there are chances that there is something wrong with your link profile.

However, there are various tools like Ahref, Semrush where you can look at your link profile and check what kind of quality links are pointed to your site. If there are spammy and irrelevant links are pointed to your site with irrelevant or spammy anchor text, then you need an urgent link audit; otherwise, anytime your site gets a manual or algorithmic penalty.

First, you have to identify all the bad links that are pointed to your site. Then you have to outreach webmasters of those spammy sites and request them to remove bad links.

Even after request, if they don’t remove the link, you can request Google not to consider those links with the help of Google Disavow Tool.

Here are the following factors you should consider while identifying a good or bad link.

Bad links

• Unnatural or over-optimized anchor.
• Irrelevant links to your niche.
• Un-moderated forum, directory and comment links.
• Links from the poor site or self-created site (PBN) with thin content without any add-on to content and user value.
• Links made by black hat tactics like links blast by automation link building tools, poor self-created web 2.0 links, and many other links build by using black hat tactics.
• Backlinks from link farms with high OBL.

Good links

• Relevant to the niche.
• Natural and branded anchor text.
• Editorial and naturally mentioned links by high-quality websites.
• Come from a real site with traffic, not from PBN and poor guest post seller. They are naturally acquired over time.

Negative SEO refers to the practice of using black hats and unethical techniques to sabotage a competitor’s rankings in search engines. 

Negative SEO attacks can take many different forms, like hacking your website, building hundreds or thousands of spammy links to your website.

As mainly webmasters don’t demand money. If they demand money, then either pay if you think that there is worth in it (not recommended) or submit that URL to the Google Disavow Tool so Google will not consider it while ranking your site.

Google’s link disavowal tool allows publishers to tell Google that they don’t want certain links from external sites to be considered as part of Google’s system of counting links to rank web sites.

Google Penguin is a Google algorithm update that was first announced on April 24, 2012. The update aimed to decrease search engine rankings of the sites that are involved in increasing the ranking of a webpage by building spammy and low-quality links.