Usage of @see in JavaDoc?

When do I use @see when dealing with JavaDocs? What is its usage?

For example if MethodA calls MethodB then do I have to put @see in MethodB's javadoc and reference MethodA because that is what called it, or do I have to put a reference to MethodB from MethodA because it's calling it. I've read the stuff about @see on the Oracle website and it seems to me to be incredibly vague, it says it means "see also" but not really what that means!

Yeah, it is quite vague.

You should use it whenever for readers of the documentation of your method it may be useful to also look at some other method. If the documentation of your methodA says "Works like methodB but ...", then you surely should put a link. An alternative to @see would be the inline {@link ...} tag:

/**
 * ...
 * Works like {@link #methodB}, but ...
 */

When the fact that methodA calls methodB is an implementation detail and there is no real relation from the outside, you don't need a link here.

The @see tag is a bit different than the @link tag,
limited in some ways and more flexible in others.
The following examples are from Eclipse:

^{Different JavaDoc link types}

1. Displays the member name for better learning, and is refactorable; the name will update when renaming by refactor
2. Refactorable and customizable; your text is displayed instead of the member name
3. Displays name, refactorable
4. Refactorable, customizable
5. A rather mediocre combination that is:

• Refactorable, customizable, and stays in the See Also section
• Displays nicely in the Eclipse hover
• Displays the link tag and its formatting when generated 😞
• When using multiple @see items, commas in the description make the output confusing

6. Completely illegal; causes unexpected content and illegal character errors in the generator

See the results below:

^{JavaDoc generation results with different link types}

Best regards.

@see is useful for information about related methods/classes in an API. It will produce a link to the referenced method/code on the documentation. Use it when there is related code that might help the user understand how to use the API.