My youngest now 14 months, bites like crazy.  At times, I think it's his teeth coming in, but other times, it is clearly just for fun.  He even kisses by biting!  If I don't like it, I touch his lips firmly with my finger and say loudly, "no biting."  This seems to help.  If you start associating words to the behaviour, he will begin to understand what he's doing and when you're not happy about it!

hi

i think his teething hun & when my boy & girl was going through that, i would give them wet face cloth to bite on or even those flavoured ice sticks as it numbs the gums & it really does work..

best of luck

It''s probably his teeth growing, I can't think of anything else.