According to the Jewish alphabet Waw is the 6th letter which also represents number 6 as a numeral.
In the Greek alphabet the extinct letter Stigma ς also represents number 6 as numeral, occasionaly still in use as such in Greece. As a letter it is still used as a final s .
In the coptic alphabet (which is almost the Greek alphabet - before the Arabic alphabet was imposed by the muslims on the original Egyptians, the Christian Copts) ς is the 6th letter and 6 as a numeral.
The Greek Stigma is a form of the Greek digamma which according to the wikipedia: Digamma (or wau, uppercase Ϝ, lowercase ϝ; as a numeral symbol: stigma, ϛ) is an archaic letter of the Greek alphabet which originally stood for the sound /w/ and later remained in use only as a numeral symbol for the number "6".
It is noteworthy that digamma is also named as the Jewish Waw.
In the Greek keybords both W and ς are on the same key.
So when you type for a website WWW or accidentaly ςςς in both cases you type 666.
This would explain why the meaningless introduction of www was introduced before websites.
The three waws.