Let's start with the term "democratic." Democratic relates to the system of government known as democracy, wherein a nation is ruled "by the people." Many of the most enlightened political thinkers throughout history believed that a democracy is the ideal form of government, as people could only be happy if they governed themselves. In terms of how this is accomplished, it could be quite literal. Small groups of people could create a democracy wherein every single person where somewhat directly responsible for their own governance. However, far more commonly, this is done through representatives by way of a republic, such as in the case of the United States.
In the middle of the spectrum exists authoritarianism. This is when a single political entity imposes its political will upon the people of a nation or state. Authoritarian leaders often obtain their power through means that are not considered legal under the normal mechanisms of the state. However, they can also establish themselves by way of rapid and situational changes to legislation or constitution, creating a situation wherein a society may not notice authoritarianism taking hold until it is much too late. An authoritarian system seeks sovereign rule over a political system with no checks to its power.
Finally, a totalitarian government is an authoritarian system that goes further than simply controlling the political system of a state or nation. Totalitarianism involves the control of every aspect of life within a country, including religion, media, ideology, and culture. Totalitarianism can be described as cultism on a national scale, as it shapes the very values and beliefs of its citizens. Often times, those who do not conform to the prevailing ideologies involved in a totalitarian society are met with social ostracism or even violent punishment.