What does the Humane Society do with the lost/stray dogs if no one claims them?

I was walking my dog this morning and ran in to 3 other dogs - 2 boxers and a german sheppard. The 2 boxers had nothing, no collar or anything, the sheppard had tags but seemed very shy and kept backing off when i got close to look at them. Also - i have seem this same sheppard many times before just wandering around so i dont know if he just gets out a lot or if the owners just have never looked for him. Anyway, they (all 3 of them) followed me and my dog all the way home so i called the human society and put them in my back yard. They are supposed to come get them sometime today but i want to know what will happen to them if no one claims them. Does any one know?