Octets are now the standard size for bytes. This allows 128 extra code points for extensions to ASCII. A number of different code sets to capture the repertoires of various subsets of European languages are the ISO 8859 series. ISO 8859-1 is also known as Latin-1 and covers many languages in western Europe, while others in this series cover the rest of Europe and even Hebrew, Arabic and Thai. For example, ISO 8859-5 includes the Cyrillic characters of countries such as Russia, while ISO 8859-8 includes the Hebrew alphabet.
The standard encoding for these character sets is to use their code point as an 8-bit value. For example, the character 'Á' in ISO 8859-1 has the code point 193 and is encoded as 193. All of the ISO 8859 series have the bottom 128 values identical to ASCII, so that the ASCII characters are the same in all of these sets.
The HTML specifications used to recommend the ISO 8859-1 character set. HTML 3.2 was the last one to do so, and after that HTML 4.0 recommended Unicode. In 2010 Google made an estimate that of the pages it sees, about 20% were still in ISO 8859 format while 20% were still in ASCII (Unicode nearing 50% of the web).