Extremal problems are at the very heart of graph theory. Interpreting it broadly, extremal graph theory encompasses most of graph theory, in its narrow sense, it contains many of the deepest and most beautiful results in graph theory.

Auxosporulation [is] the formation of an auxospore...usually a zygote, produced by diatoms, which expands to near the maximum size of a given species.

Deep beneath the ocean, the Titanic was lost to the world.

They all yelped, I remember, like a kennelful of puppies. It was their preposterous claim that I should read their hare-brained literature which caused me to display some little heat.