Young children, from infancy until age 5, are particularly at risk of choking. Not only do they have small airways, but it also takes several years to master the ability to chew and swallow food. It's very important to avoid foods that are hard or round or even slippery. Examples include whole grapes, hard candy, chunks of hotdogs or other meat. Sticky foods such as peanut butter and marshmallows should also be avoided. And don't give young children popcorn, raw carrots or nuts. Uninflated or broken balloons are also a choking hazard.
Be very careful about batteries, especially button batteries, coins, magnets, any toys with small parts. If a toy can fit inside a toilet paper roll then it's probably too small for a young child.
If you suspect your young child is choking then there are a few things you could do. For infants under the age of 1 you would lay them face down on your lap and give 5 back blows. If the child is still choking, flip him on his back and you would deliver 5 chest thrusts. For children over the age of one, do an abdominal thrust five times in a row, just as you would an adult.