Where did Catholics and Catholicism come from? Catholicism seems to have begun so quickly after the dispersion of the Apostles that I'm wondering where even it even came from.

I'm especially curious to know when Christians began calling themselves Catholics instead of...Christians:


  Acts 11:25-26 ESV So Barnabas went to Tarsus to look for Saul, and when he had found him, he brought him to Antioch. For a whole year they met with the church and taught a great many people. And in Antioch the disciples were first called Christians.


Assuming we know when it happened...I'm equally curious as to why it happened.
I don't think they called themselves Catholics instead of...Christians. They called themselves Catholic and also as Christians. Just like Catholics do even today.

Incidentally the same place where Christians got their name as Christians, is the same place where the Church was first called Catholic. That is at Antioch. The very first reference to the term Catholic is found in a farewell letter by St. Ignatius, Bishop of Antioch. Around the year A.D. 107, he wrote, "Where the bishop is present, there is the Catholic Church" (To the Smyrnaeans 8:2). Note that he doesn't explain what the term means. Thus, the second century of Christianity had scarcely begun when the name of the Catholic Church was already in use.

In the English language, the first known use of the term is in Andrew of Wyntoun's Orygynale Cronykil of Scotland (~1420 AD), "He was a constant Catholic/All Lollard he hated and heretic." (src)

The reason why they used the term Catholic is because they believed being universal, that is being same everywhere with regards to what was believed, is one of the four marks of the true Church.