Even the word for letter, which is "Ot" means sign or wonder, so you can begin to see the many religious affiliations. It's also becoming a pretty big trend in the tattoo industry. Hebrew started out with no vowels and they weren't introduced into the language until the 2nd half of the first millennium, therefore there are no vowels found in the Torah or in most ancient religious documents.
The four main periods of Hebrew are:
* Biblical Hebrew also known as Classical Hebrew which was used in synagogues and temples for worship and studies. It is not commonly spoken in it's pure form anymore but it is taught in many public schools in Israel and it's use continues in religious texts.
* Mishnaic Hebrew is the next phase of the language and it descended right from Biblical Hebrew. Although there are similarities, the differences are found in some of the grammar and vocab. Later, it was no longer in use as an oral language.
* Medieval Hebrew came next and it was used to translate Arabic works into Hebrew. It was quite different from the older forms of Hebrew and was created out of a desire to express scientific and philosophical ideas and concepts from Classical Greek and Medieval Arabic and consequently borrowed grammar and terminology from these languages.