To be an otaku, one must know the proper suffixes to use—and how to use them. How can you tell when someone is using a suffix? Well, let me introduce “Jane Smith” and “John Brown” for the sake of clarity. In general, Japanese suffixes can be used with first names or last names, unlike “Mr.” or “Mrs./Ms./Miss” in English, which are usually used only with one’s surname.

In everyday life, “-san” (as in “John-san”) is the most common suffix and can be used whenever there is doubt about other forms, although I’ll be covering others in this article as well.

–sama: More formal than -san, used with one’s superiors. Example: “Smith-sama” is the rough equivalent of “Madame” or “Lady” Smith.

–chan: A more affectionate term than -san, used mainly between friends, family members, and children. Example: “Jane-chan.”

–tan: A slang version of -chan. Example: “John-tan.”

–kun­: Similar to -chan, usually reserved for boys or young men. Example: “John-kun.”

–shi: An intermediary form between -san and -sama in terms of politeness, and mostly used for professionals. Example: “Brown-shi.”

Sensei: Used for anyone with a knowledge superior to one’s own; most commonly used when addressing doctors, teachers or professors. Unlike the other suffixes so far, “sensei” can be used alone, without a name before it, just like “doctor” or “professor” in English. Example: “Brown-sensei” or just “Sensei.”

Sempai: Similar to sensei, a common way of addressing someone with more experience or a hierarchical superior; can also be used with a name or alone. Example: “Jane-sempai” or just “Sempai.”

It is possible to change the suffix, and politeness level attached to it, that you use with one particular person. That means that “politeness” in Japanese is situational and not a fixed status given to someone, as in most European languages. You could call a friend or relative alternating suffixes. For example, if Jane and John met for lunch, Jane could say, “Hello, John-san, how are you?” Then, later in the conversation, she could refer to him as “John-kun” or even, if she wanted to be cutesier about it, “John-chan.”

There are other, less well-known suffixes, including those used for royalty, impolite suffixes that show lack of respect, combinations of two of the above—such as the combined form of -chan and -sama, “-chama,” which is usually used by children addressing an elder with whom they’re on friendly terms (like one’s grandmother). However, when in doubt, using -san is a safe bet. If you’re speaking to someone you know is hierarchically above you and you want to make sure you don’t offend, -sama will do just fine.

The definitions and explanations in this article are largely courtesy of Japan Reference and are accurate as of the time of printing.