What does 'being an expert' truly mean?

We have all heard the term 'expert' mentioned countless times whether being applied to investing, health, fitness, relationship, politics, career etc. These 'experts' are seen to be the best of the best in their particular field and are turned to provide the best or most appropriate answers or solutions to any related matters. They are also paid the most to provide their time and knowledge.

But what does being an 'expert' truly mean?

Does it mean the most education or the one who knows the most, the one who can best apply their knowledge to real life situations, the one with the best results? Or does it simply mean the one who has convinced the most people that they are indeed an expert?

There are a lot of people who claim to be experts in their field who indeed have not proven that they indeed even an good at that they do. Most television experts are not experts but they have created a brand that makes them appear to be an expert to the public. This leads to TV ratings and thus their brand is sustained. Many financial and investment experts are not personally successful but through clever marketing appeal to the public's perception of what an expert is and thus become experts. Sports commentators are not necessarily experts on sport or politicians on politics. Sportspeople are good at a single role in a sport not all roles and politicians are not experts in politics simply because they were in politics. Real estate agents are again not necessarily experts in valuing a property but perhaps very good at sales.

The point I'm trying to make is don't be fooled by people who claim to be 'experts'. Whilst some truly are (though there is no set definition or classification) many are self proclaimed and are experts through clever PR and marketing. My advice before hiring an experts is to do your own reseach (DYOR) and see if it compares to that of an expert....it might only be the difference between yourself and an expert is reading a couple of pages of a book!