Character sets:

Character sets and Language encoding

In order to write web pages in languages using characters not found in the standard ASCII 7-bit, you need to specify the character set. If the page has been made correctly, the reader still may not be able to read the page if they don't have a corresponding font installed.

ISO 8859-7, Greek

For Greek, mathematics, and other uses:

The upper 128 characters are defined differently in different languages. The ISO has developed the following standard sets and are in wide use. There are other character sets, such as KOi8 and JCK.