I usually just walk around the house in socks, but as I get older ... my feet get cold.  These are more comfy than socks (arch support), but they're like walking in a cloud -- only warm.  I wear size 5.5 shoe (except open sandals), so bought these in size 5.  Good choice.  They fit perfectly.  At first they bugged me when walking because of the low back, but I'm totally over it.  Sometimes I wear them all day -- without feeling too dorky.