Modern liberals place great emphasis on rational social planning and the use of government to solve social ills; conservatives emphasize the importance of tradition and spontaneous order; moderates are individuals whose political views are in between liberal and conservative extremes. In their current usages, liberal, conservative and moderate are fairly recent terms. As a result, their precise meanings are in flux.
According to Regis University, modern liberalism is a derivative of the classical liberalism that influenced America's founders. Classical liberals were highly concerned with freedom, individual rights and limited government. Modern liberals are likewise concerned with freedom and equality, but they favor the use of a strong central government to protect people's rights and expand their opportunities. In particular, liberals support regulation of the economy and social welfare.
Conservatives are skeptical of deliberate change to the status quo. They have less confidence than liberals in the power of human reason. Instead, they emphasize the importance of religion and tradition. Conservatives believe that society organically grows and improves with limited intervention. As a result, they usually favor minimally regulated free market economics and social welfare.
Moderates do not have a specific political doctrine. They may hold any of the positions of liberals and conservatives. Moderates are simply people who try to avoid radical extremes by choosing the middle road between the two ideologies.