When you think of microcosm, picture your home town inside a snow globe. The teeny tiny city is a microcosm of the one you live in. It is that place in miniature.
Microcosm can be used to describe anything that is a miniature representation of something else. Think of a specific event that symbolizes the way things always seems to go, like the way a kind act by your mom can represent the caring relationship you have with her. That weekend with your partner that started with laughter but ended in tears? That's a microcosm of the whole lousy relationship. The dance where you regretted your outfit, giggled with friends, annoyed a teacher, and missed your chance at dancing with your crush? A microcosm of high school.