ssentially subrogation is where someone pays monies owed by someone else e.g. insurance if you crash you car and damage someone else's car and your insurer pays for that damage, the insurer has subrogated

1. the debt is cleared

2. only when the full debt is cleared are the claims to that money settled

3. anything that the debt might be secured against, like a property

"A person that discharges the debt of another will be subrogated by operation of law to the claims of the creditor whose debt is discharged. These rights can be, and typically are, waived by the grantors of third party security, at least until all of the debt in respect of which the security has been granted has been discharged."

I could not understand the logic here.

1. what does it mean by "be subrogated to the claim of the creditor"?

2. why does the grantor waive such right?

3. what is "third party security"?

Anyone can help me? Thanks a lot.