Guardians are individuals appointed by a court to protect an "incapacitated person".
An "incapacitated person" is a person who is unable to make decisions about their own care - it does not mean that they are "bad" or "foolish".
Only a judge can decide that a person is "incapacitated", and only a judge can appoint someone to be a guardian.
A "guardian" is someone who is totally in charge of another person's affairs. A "conservator" is someone who is in charge of another person's financial affairs.
Guardianship restricts the decisions that a person may make. A guardianship should be sought as a last resort, when there are no other options left. A guardian may be limited to making specific kinds of decisions, rather than all decisions, if the court decides the limits are appropriate.