Gagging and coughing is common and normal, especially when kids start eating foods. Choking is when something is lodged in the airway and makes it difficult to breath or stops breathing until it is dislodged.
What are your experiences with infants and kids and first foods? I've seen infants cough and/or gag with foods, but luckily I've never been with an infant who has started to choke. I have the knowledge to help, but knock on wood, I'm ok if I never have to use it!