The baseline type — deceptively versatile, immune to Ghost.
Normal-type Pokémon are the default of the Pokémon world — the rodents, birds and beasts you catch in Route 1 and underestimate until one of them ends up sweeping a tournament team. They have no defensive resistances but a single crucial immunity: Ghost moves pass straight through them. That one-line quirk has kept Normal viable in competitive play for every generation since Gen 1.
Normal is a support and utility type. Its trump card is access to wide, type-neutral coverage: Hyper Voice, Body Slam, Return, Double-Edge and Boomburst hit almost everything for neutral damage, meaning Normal attackers rarely dead-draw into a wall. The downside is that Normal moves are never super-effective, so Normal mons lean on secondary coverage and setup moves to close games.
Body Slam (paralysis chance), Return/Frustration (max power at max happiness), Boomburst (140 BP, sound move) and Extreme Speed (+2 priority) define the Normal movepool. Snorlax's Body Slam para is one of the oldest cheese strategies in the game.
The first Pokémon ever shown to the public was Rhydon — a Ground/Rock type — but the most-encountered Normal-type in Gen 1 was Pidgey, which appears in Red's opening Route 1 grass within ten steps of Pallet Town.