Government Spending vs. Revenue
The classical view in democratic countries is that the government taxes the citizens to finance its spending. The Congress on the federal level and the legislature on the state level debate a yearly budget to spend the tax receipts on the different priorities. The government may raise the tax rates if it needs to spend more money that it bring in tax revenue. The reality of democratic politics is far from that classical view. Raising taxes and cutting government spending are both politically unpopular options, so governments use deficit spending.
To finance the deficit the government issues bonds and sell them to creditors. These bonds have different maturity dates, interest rates, and sale prices depending on the creditworthiness of the government, and they add a new item to the government’s budget which is the debt service for paying the interest rate on outstanding bonds and paying the face value of matured bonds. Because of the same political factors that prevent raising taxes and cutting government spending the government ends up having a deficit every year and these deficits accumulate and increase the government debt.
A common way to express the debt is as a percentage of the Gross Domestic Product (GDP), this gives an indication of the size of the debt in comparison to the economy. The debt to GDP ratio might hide the debt increase if the GDP grew at a higher rate than debt for few years, so it is important to look at the absolute value of debt as well. The following chart shows the growth of the federal debt as percent of the GDP:
