Friendship

"Friendship is a type of interpersonal relationship that is found among humans and among animals with rich intelligence, such as the higher mammals and some birds. Cross-species friendships are common between humans and domestic animals. Less common but still of note are friendships between a non-human animal and another animal of a different species, such as a dog and cat. Individuals in a friendship relationship will generally welcome each other's company and often exhibit mutually helping behavior. Friendship is generally considered to be a closer personal relationship than an acquaintanceship, although there a range of 'degrees of intimacy' in both friends and acquaintances. For most people, there is an overlap between friends and acquaintances."