Professionalism – what does it even mean?

“Professional appearance”. This is a requirement often mentioned in job offers for someone who deals with people, such as a company representative, sales rep, customer service agent or purchaser. In sales, “professionalism” is highly appreciated as a trait of the best salespeople. Yes, we all want to be professional and we want to work with professionals, but what does this even mean? And what can we do to become more professional?