Visa applications can be simple in some cases and time-consuming and cumbersome in others. You can often apply for a visa to your desired country online through an electronic system.
Travelers to the U.S. can use the ESTA system, which allows them to obtain a 90-day U.S. travel visa for up to 2 years.
Other visas, however, require finding and printing forms and sending them in the mail for approval. Then, you must wait for that approval or denial, which can take weeks or even months.
You will need to research your particular situation, as there are too many to list here.