Market – Where those wishing to buy goods/services can make contact with those who have them to sell; an area where commercial dealings take place
Note: The key to understand the word, "Market," is to realise the importance of the words, "Where they make contact."
The definition of market is self explanatory, if you consider the traditional market places that have been a standard feature of daily life for centuries. The word market, however, in business terms, has been expanded to include trading electronically such as on the internet.
Marketplaces are locations were people regularly gather for the purchase and sale of food, livestock and other goods going back more than 3000 years. Markets have been in existence as long as humans have engaged in trade. In different parts of the world they have their own names such as bazaar (Persia) and souk (Arabic).
Now many goods are bought and sold over the internet with the transfer of money completed electronically and delivery of goods directly to the home. This is still considered a marketplace, just the modern day equivalent.