There are some words and phrases: До свидания, пока, до встречи, до скорой встречи, до скорого, увидимся, удачи, давай.
До свидания is formal polite form of “good bye”. It is used for people whom you don’t know or who is much older than you;
Пока is informal goodbye, used usually by friends, it literally means “bye”;
До встречи literally means “Until next meeting”, it is used for any person if you are going to meet again; Formal and informal.
До скорой встречи is similar but literal meaning is “Until soon meeting”, it alludes to a soon meeting;
До скорого – the same as До скорой встречи;
Увидимся – see you;
Удачи! – Good luck!
Давай! – this is a form of “bye” used by close friends. You can hear “давай, пока“.