Transmission

Transmission seems to always start downloads by saying it’s Verifying Local Data, with percentage complete figures. On some occasions, this takes quite a long time

I tried to put a screenshot in here, but couldn’t figure out how to do it

Can anyone please tell me what is meant by local data? What local data is being verified? Data on my client? Data referenced by the torrent file?

Thank you

It's verifying data chunks you currently have so it doesn't need to redownload those chunks. Large filed to take a while to verify.