Today it is known that many more factors affect what effects a particular cannabis strain will have. However, the labels indica and sativa are still used by growers and sellers to give customers an idea of the type of effects a given strain may produce.
There are also hybrid cannabis strains. The reality is that today nearly all strains are hybrids. However, when the term is used commercially, a hybrid strain is one that brings together some indica and sativa effects and is quite balanced between the two. When you browse cannabis strains by type, whether you are looking at hybrid, indica or sativa, you will be able to gain a sense of what effects each provides by looking at its profile. Essentially, while the terminology may not be perfect, it is enough to point you in the right direction when looking for particular effects.