It is common courtesy to seed back as much as you downloaded (if you download 1gb you should upload 1gb back to the torrent). It doesn't have to be continuous, you can leave and rejoin the torrent as you wish, and do other stuff on the internet at the same time (unless you connection is very slow or something), if downloading/leeching the torrent will resume where it left off, if uploading/seeding you will continue to upload.
|