In a nutshell
A binomial heap is a priority queue built so that merging two heaps is cheap. It is a forest of small trees whose sizes are all distinct powers of two — 1, 2, 4, 8 — mirroring the binary digits of the item count. Inserting adds a single-node tree and then 'carries': whenever two trees are the same size, the one with the larger root is hung under the other, rolling up to the next size, exactly like adding 1 in binary. Because the trees stay small and few, insert, union, and removing the minimum all run in O(log n).