Yes, you can use non-latin Unicode characters in your web pages; however, not all browsers include all character sets by default. Some browsers are capable of installing foreign-language character sets when needed; nearly all can install them if the user chooses to do so. This does not mean that you can provide your own custom characters and invent your own custom fonts; there are ways to do this in theory, but they are not well supported by all browsers. If you must invent completely unique characters, you should use images for this purpose, and use them as little as possible. For more information about support for non-Latin characters in web browsers, check out the excellent alanwood.net Unicode pages.
