How does Time Machine work?

[chrisman9]

Dear Macsters, Ive been gradually transferring from a old Laptop (~2013) files that were backed up on an external harddrive. Having it plugged in to my iMac, I get a window stating "do you want to use BackupDrive (500.11GB) to back up with Time Machine ? What does this mean?

does the 500GB represent the size of the Data on the external HD? And, for the record I dont want to load everything--I want to be selective. Thanks for your help

 

[jbarley]

Take a look at this support link.
https://support.apple.com/en-ca/HT201250

 

[chrisman9]

Take a look at this support link.
https://support.apple.com/en-ca/HT201250

Dear jbarley, thanks for the link. I want to purge the 2007, or so, files on it before giving the Go to backup my 2014 iMac. Thanks again