Who Discovered America Before Christopher Columbus?

I learned in school that Columbus discovered America but that is not true. Who discovered America before Christopher Columbus? I'm writing an essay and for part of it I need to know who discovered America.
How do we know that Christopher Columbus really discovered America? Everyone recognizes that many people were in America long before Columbus.
Also some mention other people came to America first but they weren't so interested in invading the territory so they left and never came back.
Did the Chinese people find America before Christopher Columbus?

Well, Columbus never actually found America. He did find Caribbean islands, Puerto Rico, Cuba and South America.
A great many people discovered America before Columbus set sail. Columbus frequently gets the credit for being the "first" due to good press and the fact that his voyage was the one that began a period of exploration and colonization in the Americas.

Some historians believe that the true discoverer of the New World was a Portuguese navigator. Who he was or when he made the first dramatic landfall they cannot say. From time to time, they thought they had their man (Pedro de Velasco in 1452, João Vaz Corte-Real in 1472), but each time they abandoned the claim under sharp questioning by Columbus’ defenders.

These are some of the people historians consider to have discovered America: Columbus (1492), Leif Ericson (1000), Saint Brendan (545) or Hwui Shan (458).

The important point about Columbus's discovery was that it led to a continuous stream of further voyages which connected Europe and the Americas and totally changed the history of both continents.