I know for many of you out there, these honorific titles may be a very simple thing for you. Especially for those who are constantly watching Anime or reading Manga series. However, don’t go assuming that everyone knows the differences. In fact I had to wikipedia and read some blogs dealing with this before I learned about each title.

As you all know, I cannot speak Japanese, however, I feel that I have researched this enough to give a brief explanation of Japanese honorific titles.  So let us begin!

I will be using excerpts from tofugu.com because he did a great job explaining the titles, much better than I ever could.

San:

Overview: This is the most common. It can be used on boys or girls. It can be used in formal and (somewhat) informal situations. Pretty much, san is your fail safe when you don’t know which one to use. You probably won’t get in trouble if you use this one, so it’s good to use with frequency.

Do Not: Refer to yourself as [your name]-san. This is very rude. You might as well start asking people to get on their knees and bow down to you. Only use this on other people.

Other Uses: You can also attach san to some nouns, usually jobs. For example, booksellers are called honya-san. I know that some uses like this are more common than others so I’d say it’s best not to jump to conclusions and start turning every noun you see into name-honorific enders.

Trivial Fact: Ever notice how a lot of Japanese user names on the net end with three? I just read this on Wikipedia, and it completely makes sense. Since the number three in Japanese is san, some people use this to end their names. I think it’s clever, anyways.

Sama

Overview: Most likely, you’ll never run into an appropriate situation to use sama,
unless of course you want to be a little sarcastic. The only time
you’ll be using sama is if 1) you’re working for a company and you’re
talking to a customer, or 2) you want to be sarcastic about someone who
thinks really highly about themselves.

Do Not: EVER refer
to yourself as sama…well, that is, unless you’re making fun of
yourself. Otherwise, there’s no reason to do it, and if you do it with
a serious face, people will think you’re a big stuck up snob.

Trivial Fact: Apparently, there’s also a “Chama” version of sama. Typically, you would use this when talking to someone who is older.

Kun

Overview: This is where you start getting more casual. Kun is primarily used when referring to other males, usually by someone of high status to someone younger / lower status than them. A good example would be a teacher talking to a (usually male) student. Some (masculine) females get called (name)-kun, though this is less common.

Do Not: Use this on someone of higher status than you. That means teachers, people that are older than you, parents, etc. You get the picture. If you aren’t sure, then just use san – at least you’ll be safe that way.

Chan

Overview: Now we’re in deep waters. Chan is primarily used on children, female family members, lovers, and close friends. Really, it’s a term of endearment. Often times, one’s name will be shortened to add chan to it.

Do Not: (once again), use it on anyone of higher status than you. If you are using chan, the person should be much younger, or you better know that person really well.

Trivial Fact: Unlike all the other name honorifics, it’s actually not too horrible to refer to yourself and add the chan to the end. Children do this a lot, but so do some adults. Adding chan to a name can sometimes become a nickname that’s used instead of the real name, at which point it becomes acceptable to refer to yourself while using the honorific.

Another interesting thing about chan is that it is paired up with ojii and obaa (oji-chan / oba-chan), roughly meaning grandma and grandpa. Once Gma and Gpa get old, they come full circle, and you get to use the honorific reserved for children on them. Poor guys.

Excerpt from: tofugu.com