@w{ }A colon (:) indents a line or paragraph.

A newline starts a new paragraph.
Should only be used on talk pages.
For articles, you probably want the blockquote tag.

@w{ }We use 1 colon to indent once.
@w{ }@w{ }We use 2 colons to indent twice.
@w{ }@w{ }@w{ }3 colons to indent 3 times, and so on.