•Why it earns a slot
The play is the foundational English comic treatment of love's irrationality, weaving together three distinct social worlds and introducing the sustained theatrical metaphor of dreaming that Puck makes explicit in the epilogue, making it a touchstone for every subsequent comedy about the gap between imagination and reality.
Four young Athenians flee into an enchanted wood where the fairy king Oberon, quarreling with his queen Titania, uses a magical flower-juice to manipulate who loves whom, causing comic chaos before all is set right. A troupe of bumbling craftsmen rehearse a play in the same wood, and their weaver Bottom is briefly given an ass's head and adored by the spell-struck Titania. By morning the lovers are correctly paired, Oberon and Titania are reconciled, and the craftsmen perform their hilariously inept play at the triple wedding feast of Theseus and Hippolyta.
This distillation is written from the freely available original, which is always the better read when you have the time: gutenberg.org.