In lesser words, the Republican Party aka GOP is one of the oldest political parties in the world. They value overall conservatism and corporate liberty rights. It was founded in 1850s and they're derived from the Republicans that took part in the Civil War-Antislavery.
The Democratic Party we know nowadays is the same that supported slavery and the advent of the Civil War. It was formed in 1792 by supporters of Thomas Jefferson when they started using the term Republicans to highlight their anti-aristocratic policies. It is THE oldest political party in the US. It opposed civil right reforms after the Civil War and has gone through several reinvented beliefs in order to retain support form voters.
Hope this helps!