There are many definitions of "liberalism", and it can be confusing if you don't have additional information. In a sense, one's definition of what a liberal is has only to do with geography. As with the metric system and the enjoyment of football (soccer) as a sport, the United States is something of an exception in what it defines as a 'liberal'.
Classic Liberalism, which includes the concepts of natural rights, utilitarianism, economic liberalism and social Darwinism, emerged alongside the rise of capitalism to reflect the political interests of the burgeoning middle classes. During the transition between absolute monarchies to constitutional governments, liberalism articulated the rights of those outside the traditional power structure to freedom from arbitrary rule and economic restrictions. Today, this form of liberalism is called conservatism in the United States and is generally associated with the policies of the Republican Party (or the Libertarian Party). In Europe, the word Liberal is generally used to describe parties further to the right (at least on economic issues) than centrist Christian Democratic parties, such as the Free Democratic Party in Germany (Die Liberalen).
When the term 'liberalism' is used in the United States today, it generally is used when speaking about the Democratic Pary and denotes the concepts of freedom, Welfarism, and Keynesianism. In the United States, liberals also champion the causes of civil rights and liberties of minority groups and advocate a great deal more social change than do their "conservative" rivals. Closely associated with this sense of 'liberalism' is the tradition of political Progressivism. Progressives first developed a welfare agenda in response to the rampant social inequality and misery that emerged in the wake of the industrial revolution and in response to the articulation of rival ideologies such as socialism. Progressives, who became a powerful force in the United States at the beginning of the 20th Century, in a sense reached the peak of their power with the Presidency of Franklin Roosevelt. With Roosevelt and his New Deal programs, the progressive agenda became the agenda of much of the Democratic Party ever since. However, in much of the rest of the world, the advocacy for a strong welfare state is often associated with social democratic (socialist) parties.