This article is from the Solid Food for Infants FAQ, by David M. Poduska email@example.com with numerous contributions by others.
In the absence of particular problems, the general rule is that all
foods are okay after a child is a year old, but you have to watch out
for choking hazards for years after that. Hazards include:
hot dogs (these must be sliced in half lengthwise, as the
cross-section of a bite of hot dog plugs the
esophagous very well)
whole grapes (same reason as hot dogs)
carrots (carrots must be cooked before being given to babies who
nuts and peanuts
round hard candies
Even an item as small as half of an (unchewable adult) vitamin pill
has caused the death of a three-year old by choking.