What is Name Recognition?

Legal Definition
In politics, name recognition is the number of people who are aware of a politician. It is considered an important factor in elections, as candidates with low name recognition are unlikely to receive votes from people who only casually follow politics. Name recognition is also considered a major obstacle for challengers hoping to defeat incumbents. Incumbents are politicians who have already been elected to a particular office, and are now running for re-election to that same office. By definition, the fact that incumbents are already in office gives them name recognition. This proves to be a huge advantage over most challengers.

There are multiple ways candidates can increase their name recognition during the campaign such as radio and television advertisements or yard signs.
-- Wikipedia