Being penalised by Google is no joke for most online businesses. Having your site basically wiped off the search results pages can be catastrophic for businesses who rely on web traffic for their business revenue! There are some steps you can take to recover from either manual or automatic penalties from Google.
The first thing to establish is exactly why your site has been penalised. There are a wide range of key algorithm updates which could be the reason for your site to be penalised. The first is because of thin or poor quality content. If your site is deemed to be spammy, with bad quality content on the pages, Google sees it as being a bad site and can inflict a penalty for this.
Another reason is if you have engaged in black hat SEO techniques such as buying lots of low quality backlinks. Whilst backlinks are an important ranking factor, these links cannot just be from anywhere – it is vital that you gain links from reputable websites which hold some authority on your topic. In the last 10 years or so, it used to be possible to purchase several thousand backlinks from mainly India, which were low quality, irrelevant to your niche, yet you could still end up ranking very well for your keywords. These days, Google are much more attentive to the types of backlinks websites gain, and the volumes too.