1.) A non-deliberate misspelling of the indefinite article "the". Most commonly arises from typing a message to another person over the internet too quickly.
2.) A deliberate misspelling of the indefinite article "the". Used most frequently by people who also use other deliberate misspellings or shortenings of words such as "u". Means roughly the same as "very".
3.) An abbreviation for "the extreme highest". Often, this is what is meant by people who misspell "the" purposefully as in (2) above.
1.) I went to teh store the other day but they didn't have any fried pickles.
2.) d00d ur all teh best ppl evar!!!11
3.) You're teh man on that server.