Each Other and One Another
We have only two of these pronouns, they come in pairs, and they typically appear as objects: each other and one another. We use them to show some sort of a relationship between two or more people or larger groups. Like this:
The two teams enjoyed the competition between each other.
Wrong: Juanita and Fred tired of criticizing each others’ political views. Right: Juanita and Fred tired of criticizing each other’s political views.
The two students disliked one another immensely.