"I"van & "F"red :D

I: “Hey dude, what`s up? Do ya know the difference between formal and informal?!”

F: “Hello, to be honest I am not quite familiar with this topic but I have heard of it.”

I: “Well, I know the difference.”
F: “Would you be so kind and explain it to me, please?”
I: “Sure, no problem!”

Every conversation we have has a register. This register is either low (informal) or high (formal). Before we start a conversation we have to make the decision if this is going to be a formal or informal talk. Sometimes we do not know if we should talk formal or if informal would be okay as well. But I think most of the time you can figure it out very easy. If you have a job interview for example, or you apply for a job or you are calling someone to get information about a certain topic you should have a formal register. Also, if you are talking to a person who has a higher position or working in public services you better stay formal. Young people often have a slang when they are talking to each other. You don't have to talk in a high register if you are talking to friends.

I: “Did ya get it?”
F: “Yes, thank you very much.”
I: “No worries. By the way, Josh didn’t send me the tickets I’ve ordered and paid for.”
F: “I have also not yet received the tickets which were ordered and paid for.”

Got the difference? Sometimes the word “you” can sound unnecessarily aggressive. To avoid this you can make use of the passive.

F: “I am quite sure he will send us the tickets as soon as he can.”
I: “I hope you’re right! See ya, mate!”
F: “Goodbye!”

 a short and easy explanation of the difference between formal & informal