what is republican?

The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the Grand Old Party (GOP). The party's platform generally reflects American conservatism in the political spectrum, in contrast to the more "liberal" or "progressive" Democrats.
The Republican Party has the second most registered voters as of 2004 with 55 million, encompassing roughly one-third of the electorate. In the 2010 elections the Republican Party won a majority of seats in the House of Representatives, the majority of governorships, as well as prevalence in the majority of state legislatures, and control of one chamber in five states. Previously, the Republican Party had held minorities in all three bodies. It will continue to hold a minority of seats in the Senate at the beginning the 112th Congress.