Guardianship (over your person) and conservatorship (over your finances) are court processes that appoint someone to make decisions for you when you're deemed unable to do so yourself, and haven't already named an agent. For solo agers, understanding these terms matters less as a goal and more as a cautionary reason to plan ahead.
Why this matters more without family nearby
Courts typically favor a spouse or adult child as guardian when one exists and is willing. Without one, the court may appoint a professional guardian you've never met, based on whoever petitions first — which could be a well-meaning neighbor, a hospital social worker, or in rare cases, someone less well-intentioned.
How advance planning avoids it
A signed, valid power of attorney and health care proxy generally prevent the need for guardianship entirely, because you've already granted the authority a court would otherwise need to assign. This is the single biggest reason elder law attorneys push these documents so consistently.