Cotton is soft and very breathable fiber. In lingerie it's commonly used on the crotch to avoid extra irritation to the intimate area.
However there's some ethical and ecological problems with cotton production. Insecticides and pesticides used in cultivation cause for example health problems for farmers, pollute air and water, damage soil and reduce biodiversity.
There are some alternatives for regular cotton. With Organic cotton production the problems of toxic chemicals are avoided. However the production consumes a lot of water. In some purposes cotton can be replaced with other fibers. For example artificial cellulose fibers have some same features. We recommend you to read about environment friendly lyocell fiber.
For example GOTS is a certification for organic cotton.