Historically, climbing began precisely with multi-pitch routes: today, crag climbing has become the preparatory training for it, but long routes remain the true pinnacle of this discipline. Whether they consist of a few or many pitches, they allow climbers to scale large walls or reach the summit of a mountain through a succession of single pitches: the lead climber reaches the belay station, sets it up and brings up their partner, rather than descending back to the ground as they would on a crag.
These routes are also suitable for those with little climbing experience: you just need to have a head for heights and a desire to climb high. Only a basic level of technical skill is required, whilst specific techniques will be taught during the outing itself.