Active Search Bar Browser Hijacker
Active Search Bar is the name of a rather generic browser hijacker and potentially unwanted program. Potentially unwanted programs or PUPs aren't on the same threat level as malware, but as their name suggests their presence on the system is not desirable.
Active Search Bar will do what most browser hijackers do - it will change your browser's default search engine used when you type into the address bar. Whatever you used to have selected before will be swapped for the activesearchbar dot me engine.
Because it is not a fully-featured search engine, the replacement from the hijacker will use Yahoo for search queries, but will also generate revenue for the Active Search Bar owner. Additionally, your search queries and browsing habits may be recorded and later re-sold to third parties, usually advertising companies.
The fact that the default search engine swap is done without the user's explicit permission is the main reason Active Search Bar and similar apps are classified as potentially unwanted programs. Thankfully, like most PUPs and browser hijackers, it has next to no persistence mechanisms and removal is not problematic.