Every once in a while, I refer to a “type” or “typology” is something I write or speak on. What follows is a brief explanation of what that is, excerpted from a longer piece I wrote.
A very important device in the study of the Old Testament is what we call “typology.” Typology is employed under the inspiration of the Holy Ghost by New Testament writers. So what is it? The Greek word typos, meaning “blow, impression, or model” gives us the English word “type,” from which we get “typewriter” — which is something that leaves an impression on a page. We also get “archetype,” “prototype,” and “stereotype,” from it. A type, in the way we are using it here, is any thing (any person, event, institution, object, etc.) in the Old Testament which foreshadows some New Testament reality. The corresponding New Testament reality itself is called an “antitype.” St. Paul engages in typology — that is, the study of types — when he calls Christ the “last Adam” (1 Cor. 15:45) and says that Adam “is a figure [typos] of him who was to come” (Rom. 5:14). In this case, Adam is the type, and Our Lord the antitype.
The Old Testament is filled with types of Our Lord: Adam, Isaac, Moses, Josue, Jacob, Joseph, Solomon, the paschal lamb, the tabernacle in the desert, the temple, the brazen serpent, and many other people and things foreshadowed Jesus. Other New Testament realities were also foreshadowed. The twelve sons of Jacob were types of the twelve apostles. Joseph, “the dreamer” of Genesis, was a figure of the New Testament St. Joseph, who received messages in dreams. Saint Paul speaks of Baptism as an antitype of circumcision (Col. 2:11), while Jesus Himself says that the Eucharist was prefigured by the manna in the desert (John 6).
Fisheaters has a longer explanation, with more examples.