Small breeds suit apartment living and lower exercise budgets, but "small" covers a wide range of temperaments — from lapdog to feisty terrier.
Not All Small Dogs Are Lapdogs
Terriers bred small for vermin control — Jack Russells, Rat Terriers — retain a working drive and need real exercise, despite their size. Toy breeds bred purely for companionship, like the Maltese, tend to be more sedentary.
Health Considerations
Small breeds are prone to dental crowding, luxating patellas, and, in brachycephalic breeds like Pugs, breathing difficulty. A vet familiar with the specific breed is worth seeking out.
A Note on Handling
Small dogs are more easily injured by falls or rough handling than their size might suggest, and often benefit from consistent, gentle training to prevent the "small dog syndrome" of anxious or defensive behavior.