Generally, the Jacksonians were the common people of American society. They were the people who believed in the Jacksonian vision of mass democracy.
Before the Jacksonian era, America had been less democratic. In many states, there were property qualifications for voting. Only men (since women couldn’t vote) who owned certain amounts of property could vote. Political leaders were typically from the elite. This can be seen in the fact that all of the presidents of the US had, until that time, been rich Virginia plantation owners or members of prominent New England families.
The Jacksonians were generally those on the other side of society. They were the common people who made up the vast majority of the United States. They believed in mass democracy. They believed that the government should stop governing in ways that helped the elites and should, instead, govern for the benefit of the common people. This could be seen most clearly in Andrew Jackson’s fight against the Second Bank of the United States while he was president.
The Jacksonians, then, were the common people who believed in the ideas of populism and mass democracy that are called “Jacksonian democracy.”