Bantams are the "fun-sized" equivalent of a number of other breeds. This comes with many caveats, but it is safe to assume that when someone says "bantam," they mean a bird one-fourth the size of most others. They max out at 2 pounds.
True Bantams: are breeds with no large counterpart. They make look like larger breeds but are wholly unique.
Miniature Bantams: have a large counterpart.
Developed Bantams: are bred for a specialized purpose. All miniatures are developed. Some true bantams are developed.
Bantams enjoy roosting in high nesting boxes (1-2 feet off the ground, or more with perches), 1 box per 4 birds is a good number.
Crumble feed is appropriate for these smaller birds - each will eat a pound of food per month and need daily access to fresh, clean water.
Bantams are less hardy than their large counterparts - be aware of their coop temperature during cold seasons.