Common greetings:

• Dobré ráno! – Good morning!
• Dobrý deň! – Good day! (formal “hello” that is appropriate at any time of day)
• Dobrý večer! – Good evening!
• Dobrú noc! – Good night! (before going to bed)
• Ahoj! – hello/bye (informal; when talking to one person)
• Ahojte! – informal hello/bye (informal; when talking to two or more people)
• Čau! – hello/bye (informal and more relaxed than ‘ahoj’; when talking to one person)
• Čaute! – hello/bye (same when talking to two or more people)
• Dovidenia! – goodbye (formal)

On the phone:

• Haló? – Hello?
• Prosím? – Please?
• Áno? – Yes?