We use each other and one another to show that each person in a group of two or more people does something to the others. There is very little difference between each other and one another and we can normally use them in the same places. Each other is more common than one another:
Rick and Gina never liked each other. (Rick never liked Gina and Gina never liked Rick.)
Everyone in the family gave each other presents. (Each member of the family gave each member of the family a present.)
How’s Maria? Do you see her often?
She’s great. We phoneeach other/one anotherregularly.
We use each other’s and one another’s as possessive determiners:
Lisa and Kate hated each other’s husbands. (Lisa hated Kate’s husband and Kate hated Lisa’s husband.)
My friend Olivia and I know very little about one another’s work.
Be careful not to use us or ourselves instead of each other/one another:
We’ve known each other/one another for twelve years.
Not: We’ve known us for twelve years or We’ve known ourselves …