There really is nothing worse than getting a manual action message in Google's GWT console but there is one good thing about it.
You know quite a lot about the reason for the penalty and this gives you a huge advantage over some of the other algorithmic penalties when it can take a good amount of deduction to zero in on the problem.
There are wide range of manual actions that can be applied to your site and I'll run through most of them here.
There are two types of unnatural link penalties, the first can be ignored if you like as it won't effect your rankings. The second is used when Google thinks that you've been involved in a link scheme which is against their terms of service.
Part of the recovery process is showing Google that you have tried to get the offending links removed.
You can of course be punished for having unnatural links coming from your site. This happens when Google thinks that a webmaster is selling links or otherwise involved in some link scheme.
These different types of penalty will be clearly marked for the Irish business owner to see in GWT
Thin content is the term often used when Google thinks that your content has zero value to the visitor.
A more detailed account can be found here. But to summarise...
If a page is generated automatically from scrapped content and provides no value to a visitor then it would come under this penalty. And you do see these in the results sometimes. But it would be very unusual for a business site to get hit with this type of penalty.
When your site gets hacked it's hardly your fault in most cases but nonetheless, Google will apply a penalty and warning to you if they come across any malicious code on your site.
The quick fix for this type of penalty is to remove the offending code and scan your site to make sure everything is nice and safe.
This may be beyond the abilities of many, and of course there are numerous companies that specialise in fixing this type of problem. Sucuri are very reputable.
The pure spam penalty can cause SEOs headaches as it is more an umbrealla term that covers alot of possibilities.
Maybe Google thinks that you are using scrapped and spun content or cloaking part of your content. It can also be used to describe the quality of incoming links to your site
This type of manual action usually requires a bit of investigation to understand the true meaning.
This warning is used mainly when the webmaster is cloaking his content. And by that I mean showing one page to the Google bot and another to the actual visitor.
This redirects the visitor to something unrelated to what is shown the search results and is increasingly used against terms of service for pay per click advertising.
This type of penalty is not often seen anymore due to Google's numerous updates punishing keyword stuffing.
This type of penalty should be thoroughly investigated to make sure that you site hasn't been hacked.
Structured markup or schema was introduced to help the search engines understand webpages better and provide clear and detailed information in the SERPs. Think of the stars beside IMDB pages or a cooking recipe in a standard format which it can present to the person searching.
But having the stars beside your results gains you an advantage over the competition due to the high click through that you get with schema results.