Snowy - usually 2 reasons - teething and attention.

When DD started biting me, she was teething and i didnt want it to turn into a way for her to get a rise. SO this is what we did and it worked a treat!! only did it perhaps 1/2 dozen times in total then she stopped (will explain a little more in a sec).

When he bites you on the skin/arm etc.. scream as loud and high as you can! He will look at you with a shock and possibly cry from being scared but honestly it works!!! I had DD in tears many times then she realised what caused me to scream so lough and high pitched .

She will still come and bite my pants or shirt , but she doesnt get my skin, she is very careful now and i dont scream when she does that. she learnt the difference between good and bad biting.

Dont yell or get mad or anything else, just scream and move on....

hth for you!