Housing
Cage or Aquarium?
Some people use aquariums but I would defintley advise a cage as it gives the rats a good ventilated home as they don't want to get too hot or cold. They like to climb so this is another good reason to get a cage.
Aquariums are cheaper but it is a poor excuse for your ratty's well-being. Get as big a cage as you can afford as they like to run around, and will be spending lots of time in the cage when you're not there. If you can get one with different levels that is even better.
I have a cm x cm cage which is enough room for two rats. It is a popular cage (the Ferplast Furet Tower Cage) you can find on the internet for around £80+. Go to the Links page for a link to the cage.
Some bird and ferret cages are cheaper so one of these can be nicely converted into a rat cage. Just remember the cage needs a plastic floor and metal sides. No wood! And make sure that the holes aren't so big that the ratties will squeeze through!
What Bedding?
For the floor
There are a lot of different varieties of bedding that you can use but stay away from PINE and CEDAR as they are dusty and will irritate the rats noses and eyes and can cause long-term illness.
Wood shaving, chips, pellets and dust-free recycled paper cat litter are good options. Do not use old newspaper anywhere in the cage as the ink will rub of on the rats' feet and they will lick it, and this can be toxic for them.
For their sleeping area
They need a sleeping area. There are lots of different options but remember, it needs to be chew friendly and warm. I have a little wooden house (cm x cm) which is big enough for two rats. Just browse around your pet store but don't get anything that is for hamsters as it will be too small and flimsy.
Fill the sleeping area with paper shreddings and soft recycled paper shreddings or torn up kitchen towels.
What else do they need
Below is a series of pictures showing how to set up your cage:



This cage is too small for a rat's living quarters. The bigger the better.
Hamster cages are too small for one rat, let alone 2 or more.