A good number of countries require visa. Being granted a visa is often an uphill task, with demands made for your bank statements, proof of income to ascertain you have a job to come back to, proof of hotel bookings for where you are headed or proof you have somebody to host you, any other proof to show that you are indeed visiting to do what you are claiming is the purpose of the trip. It's an endless list of demands and they could still deny you the visa.