How to say "I'm sorry" in Russian?

How to say "I'm sorry" in Russian?

Извините! Простите! 

These mean:  "I'm sorry"  “Excuse me” or “Pardon me” 


How can you use  it?

How to say "I'm sorry" in Russian?

 You can use both in a range of situations, from such light offenses as bumping into someone to something graver, such as spoiling a surprise. 
If you are interrupting someone with a question, as when you ask for directions, it is only polite to start with извините. 

If you are saying this to a person with whom you would use an informal ты (informal you), you would say прости or извини.