A shower curtain is a boon in preventing water getting all over the bathroom floor, however it does have one big disadvantage; the likelihood of icky mold growing on it.
To prevent this from happening to yours, this article discusses some ways to prevent mold and mildew build up.
The first place to start is with the type you buy.
There are curtains on the market now that have been treated with a specific anti-mold treatment that prevents the build up of mold on them.
This saves you time on cleaning them and having to use harsh chemicals in the bathroom.
You could also buy a liner which fits in between the bath and the shower curtain itself.
By having the liner sitting on the inside edge of the bath and the curtain hanging outside the bath, no water will be splashed onto it, keeping it reasonably dry.
This will prevent any mold building up on it as mold needs moisture to grow.
If you use a vinyl shower curtain, you can soak it in a vinegar solution.
The acidic nature of the vinegar prevents the growth of mold.
Then as a preventative measure you could make up a spray bottle with 70% vinegar to 30% water and spray that along the bottom of the curtain each time you finished in the shower.
You can also use a strong salt water solution to soak a vinyl shower curtain in for a an hour or so before hanging.
This prevents mold from forming and you can maintain a mold free curtain by spraying the bottom of the curtain in a similar way as you would the vinegar solution.
Always make sure you fully draw your curtain across the shower rod to help it dry out as soon as you've finished your shower.
Leaving it scrunched up together creates an opportunistic environment for mold to grow in all that moisture.
It's also a good idea to open a window or use an exhaust fan to help get the humidity out of the room and get the air circulating.
This will help it dry out quicker, and the quicker it dries the less chance it has of developing mold on it.