Entry rules for the UAE are generally straightforward for visitors from many countries, but they do change, so treat this as a starting point, not a final answer.
The United Arab Emirates — of which Abu Dhabi is the capital emirate — grants visa-free or visa-on-arrival entry to passport holders from a large number of countries, typically for a stay of 30 or 90 days depending on nationality. Citizens of countries outside that list generally need to arrange an e-visa in advance, often through their airline or a licensed visa service, before travelling.
Because these lists and durations are reviewed periodically, the single most useful thing you can do is check your own passport's current status directly with an official UAE government source, or your airline, close to your travel dates, rather than relying on a fixed list here.
A passport valid for at least six months beyond your arrival date is the standard requirement, along with proof of onward or return travel and, occasionally, evidence of accommodation. Immigration officers at Zayed International Airport also expect standard health and customs declarations consistent with international travel norms.
If you're arriving overland from another Gulf state, such as after a trip based in Dubai or Oman, the same visa rules generally apply as arriving by air — but border posts can be slower, so build in extra time if you're on a tight schedule.
It depends on your nationality — many visitors receive a visa on arrival or travel visa-free, while others need to apply for an e-visa in advance. Check the current rule for your specific passport before booking flights.
Passport holders from eligible countries generally can, but the eligible-country list is set by the UAE government and reviewed periodically, so confirm your status ahead of travel rather than assuming.