What is the most popular horse bit?

Could you please elaborate on the concept of "horse bit" and its significance in equine equipment? Among the various types of horse bits available in the market, which one is considered the most popular and why? Are there any specific features or benefits that make this particular horse bit stand out from the rest? As an expert in the field, could you provide some insights into the factors that horse owners and trainers consider when choosing the most suitable bit for their equine partners?