PO, "Civic Platform", in English, is in orange. They are generally economically right-wing and pro-Western, and take little stance on social issues. PiS, "Law and Justice", in English, is in blue. They are socially very conservative and generally speaking populist, somewhat leftist and rural-oriented.
LiD, "Left and Democrats", in English, is in red. They are social democrats in the traditional European model. PSL, "Polish People's Party", in English, is in yellow-green. They are socialists who have reformed and might now be closer to Christian democrats in the traditional European model; hard to pin them down. LiD and PSL are less significant but win 8-15% of the vote nationwide.