Many nationalities require a visa, and a few require an invitation as well. Citizens of Andorra, Belgium, the Czech Republic, Denmark, Estonia, Finland, France, Greece, Hungary, Iceland, Ireland, Italy, Liechtenstein, Lithuania, Luxembourg, the Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland, the UK, Australia, Canada and the USA can travel visa-free for stays of up to 90 days; citizens of many countries do not require a visa if they already have one for Estonia or Lithuania
Africa
