What is politics?

According to Merriam-Webster's dictionary, politics can be defined as "the art or science of government," particularly the ability to "[guide] or [influence] government policy." The desire to guide and influence policy creates competition between "interest groups or individuals for power and leadership."
Currently, in American politics, two political parties dominate government and strongly influence its policies: Democrats and Republicans. The former group is mainly preoccupied with building a strong middle class and creating some provisions for poor citizens (e.g., Medicaid), while the latter seeks to maintain tax cuts for wealthy and upper-middle class citizens, with the belief that, with their increased buying power, this class creates more jobs for those in lower economic strata. 
One of the most controversial aspects of contemporary politics is the influence of special interest groups. These groups, mainly comprised of corporations, use their wealth and commercial influence to impact economic and social policies. They do this by providing large contributions to the campaigns of political candidates and incumbents. Some argue that politicians cannot be fully invested in the interests of less powerful voters, due to the monetary influence of special interest groups or individuals with the power to "buy" campaigns. Most recently, the influences of the Koch Brothers and the Mercer family have been cause for concern.