Generally speaking, a celebrity is someone who seeks media attention and most frequently have extroverted personalities. The desire to be notable is implied by some to be a part of western culture and more specifically the American Dream as a measure of success. Celebrities that shy away from the public eye or keep a very separate private life are called a
reluctant celebrity.
A notable example is Kurt Cobain. On the oher end of the spectrum, those that seek out publicity for themselves are often called a
media tart whereas those that use their private life as a vehicle for enhanced celebrity status, sometimes desperately, are referred to as a
media whore. Examples of this are fake or planned relationships, reality television appearances, celebrity nudity and in extreme cases, scandal or celebrity sex tape.
In some places, someone that somehow achieves a small amount of transient fame through hype or mass media, is stereotyped as a B-grade celebrity. Often the stereotype extends to someone that falls short of mainstream or persistent fame but seeks to extend or exploit it.
There are a wide range of ways people can become celebrities, from their profession, appearances in the mass media, beauty or even by complete accident or infamy. 
A global celebrity on the other hand is someone who is known by most people or is a mainstream celebrity. Such celebrities are also known as either a household name or superstar. 
A celebrity is a widely-recognized or notable person who commands a high degree of public and media attention. The word stems from the Latin verb "celebrere" but they may not become a celebrity unless public and mass media interest is piqued.
