You will see the words "nucleus colony," "nuc colony" or "nucs" on beekeeping websites or in your association newsletter. What exactly does this mean?
A nucleus colony are one way honey bees are sold. The phrase "nucleus" can also refer to a small, three- to five-frame beehive. Nucs are small colonies of bees with a queen that have already been started. Unlike package bees, the other main way to acquire bees, nucleus colonies have been living and working together with their queen for some time already.
The nucleus box is structured just like a Langstroth hive, only it is not as wide, and is only meant to hold a maximum of five frames. When buying a nuc colony, you can get three-, four-, or five-frame nucs. The number refers to how many frames the bees have filled out already with comb and brood. The more frames, the bigger the colony (and often, the more it costs).