Who fought in the Civil War?
There have been many civil wars around the world in different countries, but we assume you are asking about the American Civil War or the 'War between the States' as it was also called.
The American Civil War was fought between 1861 and 1865. In a nutshell, there were two sides who fought in the Civil War:
1) The United States, also known as the Union or North. The Northern States were California, Connecticut, Delaware, Illinois, Indiana, Iowa, Kansas, Kentucky, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Nevada, New Hampshire, New Jersey, New York, Ohio, Oregon, Pennsylvania, Rhode Island, Vermont, West Virginia, and Wisconsin. The leader and President of the United States at the time was Abraham Lincoln.
2) The Confederate States, also known as the Confederacy or the South. The Southern States where Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, Texas, and Virginia. The leader and President of the Confederate States of America was Jefferson Finis Davis.
The main reason for the civil war was because the North wanted to abolish slavery and the South wanted to keep and expand slavery. The North won, slavery was abolished, and Abraham Lincoln went down in the history books as one of United States' best presidents.