Websearch.fastosearch.info is a piece of software commonly known as PUP (Potentially Unwanted Program). This program displays particularly unpleasant ads below its search bar.
Often bundled and installed along with free software, this program will automatically redirect your web browser to Websearch.fastosearch.info regardless of what your default home page is, and will also set your default search engine to search.smartaddressbar.com.
Websearch.fastosearch.info is one of the more common types of PUP (Portentially Unwanted Program), meaning any sort of unwanted and disturbing, sometimes damaging software.
The category of malware does include some viruses but browser hijackers are usually less harmful than viruses. Hijackers remain, even in the most ideal circumstances, an intrusive annoyance and, at worst, a threat to your online security.
The purpose of browser hijackers like Websearch.fastosearch.info is to drive traffic to a particular website in order to generate revenues from the ads displayed on the search engine; every time a user clicks an ad, its distributor earns a fee.
In less common cases, a browser hijacker may try to collect personal information about you which poses a more severe security threat. Fortunately, stopping your browser from being hijacked is relatively simple, and will work across all browsers.
The hijacking is being done by a program on your computer, and all you have to do is get rid of it. To stop Websearch.fastosearch.info, the recommended solution is to manually reset your browser settings and then use the Browser Hijacker Removal Tool to prevent Websearch.fastosearch.com from reappearing.