Here it is in a nutshell. Similarly, our shirts and blouses must cover our elbows even when we reach upward. We cover our legs with stockings or tights, and we do not wear open-toed shoes. Clothing can be of almost any color as long as it is subdued and not loud.
Married women keep an additional level of tznius by covering their hair completely.
There are a few popular styles for hair-covering. In my community, wigs are preferred, because they cover the hair most completely. In the comfort of our homes, most women wear turbans, or a longer version of a turban called a snood. These are considered casual in my community, but in others, women wear them more frequently, to work, for example. And in other communities, hats are the covering of choice.