The vast majority of airsoft players utilize standard airsoft pellets, which are spherical, plastic, six millimeter projectiles. The term BB has become synonymous with airsoft pellet, although historically a BB is a smaller (around four and a half millimeters), metallic projectile that can be lethal. Besides regular pellets, there are a variety of special pellets that have been developed for a multitude of purposes, and although they are more expensive, most people find the extra cost to be worth it.
Biodegradable airsoft pellets are becoming more popular as airsoft players become more environmentally conscientious. Regular pellets have are petroleum or mineral based, and will remain in the environment for hundreds of years if not manually removed. Biodegradable alternatives are composed of materials that naturally decompose in the ground, and many airsoft fields are beginning to require that players use only biodegradable ammunition. While biodegradable pellets are not widely available currently, it is possible that in the future they will be the only option.
Paint filled pellets can also be utilized, and the benefits of these are that you can visibly see when you hit a target or opponent. The drawbacks of these “markerballs” are that they can easily break inside the barrel or other part of the gun, damaging it internally and possibly voiding the warranty. In general, it is advised that you do not use markerballs, and if you do, you should keep the use down to a minimum.
One of the most interesting types of pellets is the tracer pellet, which is luminescent and can be seen in the dark. The purpose is to be able to see where you are firing in a night game, as seeing the flight path of a regular pellet is almost impossible. To save money, tracer pellets can be interspersed with normal ammo, in varying ratios depending on the situation.
While extremely rare, there do exist various non-spherical pellets that resemble real bullets more closely than traditional airsoft pellets. Non-spherical pellets are incompatible with most airsoft models and are incredibly expensive, and most airsoft players will never even see one. However, it is good to be aware of their existence.