What kind of snake is red and black?

There are many different varieties of black-and-red-striped snakes; most infamously, the Coral snake vs. the Milk snake. Though they look nearly identical at first glance, one is deadly, and one is harmless. There is a little poem to help you remember the difference between the two.

To determine whether the snake is poisonous or not, simply look and the stripes and think of this poem:

Red on black? You're okay, Jack.

Red on yellow? They'll kill a fellow.