Perimenopause is the transition before menopause, and it commonly runs for four to eight years — long enough that many women pass through it without naming it.
Cycles usually change first: shorter, then longer, then missed. Hot flushes and night sweats are the best-known symptoms, but disturbed sleep, joint aches, low mood and difficulty concentrating are just as common and much less often attributed to hormones.
Menopause itself is a single point — twelve months after a last period. Everything before it is perimenopause, and symptoms often peak in the year or two around that point rather than after.
Bleeding that is very heavy, that returns after twelve clear months, or that comes with pain is worth medical attention rather than being filed under "the change".