The main gateway is Heydar Aliyev International Airport (GYD) in Baku, which has direct connections to most European capitals, Istanbul, Dubai, Moscow, Tehran, and major Central Asian cities. Azerbaijan Airlines (AZAL) is the national carrier; Turkish Airlines, Flydubai, and several other carriers also serve Baku. Ganja has its own small airport with flights from Istanbul and a few CIS cities, useful if you are heading straight to western Azerbaijan.
Visa: Most nationalities need a visa. The easiest option is the ASAN e-visa, applied for online at evisa.gov.az. The fee is around USD 25, and most applications are approved within three working days. The e-visa allows a single entry and a 30-day stay. Citizens of Turkey, Georgia, and several other countries can enter visa-free; check the current list before you travel. Importantly, if you have evidence in your passport of visiting Armenia, you will be refused entry — Azerbaijani border officials take this seriously.
By land from Georgia: The main crossing is at the Red Bridge (Krasny Most) near Agstafa, on the Baku–Tbilisi highway. The road is well-travelled and the border is generally straightforward. Marshrutkas and shared taxis run between Tbilisi and Baku via this route.
By land from Iran: The crossing at Astara on the Caspian coast is the most used. The Baku–Tehran bus stops here. Expect some delay; bring patience.
Border with Armenia: Closed. There is no crossing between Azerbaijan and Armenia.