To answer questions here and in responses, as to what serfs were and how distinct they were or weren't from slaves:
"Serf" is servus in Latin: literally the word "slave". Serfs began as chattel slaves on late-Roman latifundia, but were tied to the land, not to individual owners, by late Roman laws trying to fight depopulation and keep agriculture running.
In the Dark Age, the Carolingian period, and the Viking Age, slaves'/serfs' rights increased due to pressure from the Church, while free commoners' rights decreased, often also due to pressure from the Church. By the end of the Viking Age and the beginning of the Middle Ages proper, official documents spoke of "slaves free and unfree"; by the High Middle Ages, land as well as people was servile or free, so that a serf could own free land (which required a cash rent) or a freeman could own servile land (which required labor service). "Own" here meant "lease", but you could literally buy or sell the lease, or borrow money against it.
A History of Private Life, especially its second and third volumes, and Marriage and Family in the Middle Ages are excellent sources on this.
Serfdom does starts with a specific owner at the start. What separates serfs from indentured servants was: "By taking on the duties of serfdom, serfs bound not only themselves but all of their future progeny."
And of course people where at times forced into serfdom making the slavery connection even more obvious.
