At the time of the Domesday Book, (1086), in England, the population (of about 2m) was socially divided like this:

Nobility: There were about 200 Earls or Barons, including senior ecclesiastics, (plus their families).

Upper Class: Knights (about 1000), clergy, a few other categories, even with their families a small % of the population.

City and town dwellers: Estimated to be less than 10% of the population, but the cities were not well counted in the Domesday Book (London and Winchester, for example, not surveyed at all).

"Sokemen": These were freemen, who held their own heritable land (about 20% of land in England was held in "socage"). They made up about 15% of the population.

"Villani": Did not own their land, but farmed their own holdings (about 45% of English land) in return for labor or services or shares for the land owner. About 40% of the population.

"Bordars" or "Cottars": Like "villani", but held much smaller plots of land. Circa 30% of the population.

Slaves: No land at all. Less than 10% of the population.

http://faculty.history.wisc.edu/sommerville/123/123%2013%20society.htm

The last three categories might all be called "serfs" (though "slaves" had significantly fewer rights than villani and bordars), but their rights and obligations would be quite different (not only between the three categories, but also in different parts of the country and even between different manors). In general, villani and bordars were tied to the land (though if they left for a town, and were not brought back within a year and a day, they generally became untied (though they lost all their previous rights to land holdings)). Slaves could be sold as individuals (villani and bordars could not, though the land could be sold and the people would go with it, but villani and bordars could not, for example, be sold away from their spouses or children, whereas slaves could).

Slavery in England gradually disappeared over the next century after the Domesday Book, and eventually the courts interpreted the Magna Carta of 1215 as having outlawed slavery in England.

Serfdom also became less and less common, starting before the 14th century, was mostly gone by 1400, and was finally legally abolished in 1574.