The use of the word "Sie"(you), " du"(you) and "ihr" (you) is a very good example of how the german language and culture are intertwined. It is the 
beauty of German Language.
Germans are quite particular and they generally pay key interest in showing proper respect towards each other. German has a formal and informal ways of using the word "you". For german beginners choosing to know when to use informal " you" and formal "you" can be a little tricky sometimes. If you don't use it the proper way you should,they may consider you disrespectful. Therefore,it is even advisable to use only formal way to address people as a beginner in German Language.
The word "you" can come in 3 different forms in German. Let us see it below:
du(you) - It is an informal "you". It can be use for people closer to you or for someone that is easygoing. It is also use for use for a singular person.
ihr(you) - It is also an informal " you". But it's a use for plural,that's the difference between ihr and du. For example: You all
Sie(you) - It is a formal " you". It is always written in capital letter 'S' anywhere you see it in a sentence. It is use to address people outside your family and friends. It is also use for both singular and plural.
The English speakers once use that for the words thuo and thee,i believe some of us might not know this before now. #wink
Examples:
- Sprechen Sie Deutsch?(Do you speak German).formal
- Wie geht es ihnen (How are you all)formal
- Du lernst langsam (You learn slowly).
4)Haben Sie?( Do you have).
With these knowledge about the formal and informal way of expressions,you can communicate politely and more confident. I hope you enjoyed it.
Viel Dank!(thank you very much)
Bis später (see you later)