My 3 year old son throws terrible temper tantrums any tips? just screams for hours when he doesn't get what he wants whats an appropriate reaction

Anger management: Knowing what triggers his tantrum will help. Ignoring them too might help . Giving time out for about 3-4 min help him to cool down too.

Start by calling : Child Find of your local school district for developmental assessment. Also, fill out developmental screens & the M-CHAT on firstsigns.org & see his pediatrician.Tell your son your rules at his language level, then ignore tantrums consistently by walking him from behind to time-out without talking, making eye contact or acting angry. Repeat till he stays put, then set timer for 3 minutes.