Why did European companies prefer the coast to set up their trading companies?

If you talk about America -because the eastern coast was closer to Europe and the Euroeans did not know anything about the other parts of America at the beginning. By the time they did so, the big cities with prospering business life had been born.

If we talk about Africa -because the inner parts are too hot (deserts) and cannot be reached easily. Trading companies need(ed) ports because shipping goods by sea is the cheapest way of transport.