My name is Sue and I foster one cat at a time and open my whole house to the cat. It becomes their home and they adapt to my lifestyle until such times as we can find them a permanent home. The cats come to me for a variety of reasons but I have tended to specialise in abused, battered and abandoned strays, who take time to readjust to human company. Others have come from broken homes, or because owners are in hospital or jail, or, perhaps the saddest of all, when owners have to go into care homes and are not allowed to take their beloved pets.
I started fostering in 1989, a few months after losing my beloved cat, Tigger, aged 14 years. For a variety of reasons, I felt unable to take on the long-term, lifelong commitment of having my own cat again. Fostering certainly has its ups and downs and the biggest down is having to give up the abused cats when they have readjusted to all the good things in life and become cuddly and gorgeous. That's when I want to keep them and when they are most likely to be homed. But what I have to remember is that no-one really wants these cats when they are first brought in, some too traumatised to move, others fighting, biting and hissing. 
To integrate such cats and turn them into loving, homeable cats is very rewarding in its own way that's a definite 'up'. Even better when you can home them with lovely people who will give you regular updates, so you know they are doing well. When new owners and their cats are so happy, how can I be sad to let them go? And, within a few days or weeks, I am likely to be concentrating my energies on the next needy cat, who may otherwise still be in a situation of abuse without the space to bring them in. Although I only take one cat at a time, so I'm a small fish in a big pond, the benefits to me of fostering is to know how valuable even that one space is to the cats in need of a refuge, for a few days, weeks or months. One was for years but we decided not to re-home this cat when he was given just 6-12 months to live he lived happily with me for another 3 years!
Also in that big pond are the wonderful Croydon Cats Protection volunteers who dispense advice, help and back-up support. Vets bills are paid for all cats in foster care, and a very modest sum can be claimed to help with day-to-day expenses. Within reason, I can choose when to foster, and I can always have help for holidays etc. Most precious and rewarding of all are the wonderful memories of the many special cats that have come into my care and all found loving homes.