First contact is most often a science-fictional theme about the first meeting between humans and aliens. There have been entire series devoted to this theme. One classic series is the "interstellar trader" series by Andre Norton. A more modern treatment, using radio rather than spaceships, is Contact by Carl Sagan.
The theme of first contact, however, is not limited to science fiction. For example, many stories about the old American West featured a first contact between white man and Native Americans. (In fact, early Star Trek episodes seem to have been modeled after westerns.)