In 1977 NASA launched the Voyager 1 & 2 spacecraft with a mission to explore the outer solar system. They were to gather information and imagery on Jupiter, Saturn, Uranus, and Neptune. After their mission was complete they were to keep travelling into interstellar space and end up orbiting the milky way galaxy in some form.
The Golden Record was produced to be attached to the side of the craft that would be an artefact of information about humanity. Our location, our species, our arts, our environment. All would be contained on a golden disc that may end up surviving even our current planetary civilisation. If you want to know what type of images, sounds and diagrams are being used as a kind of galactic advertising, Vox.com has a good summary here.