A more thorough explanation:

Definition: Institutional gerrymandering is the practice of manipulating the number of representatives per district in order to give one political party an unfair advantage. This is done by changing the boundaries of voting districts to dilute the opposition's voting strength.

For example, let's say there are two political parties in a state: the Red Party and the Blue Party. The state has 10 districts, and each district elects one representative to the state legislature. The Red Party is in power and wants to maintain its control, so it redraws the district boundaries to pack as many Blue Party voters as possible into a few districts, while spreading out Red Party voters across the remaining districts. This means that even though the Blue Party may have more overall voters, they will only win a few districts, while the Red Party will win the majority of the districts and maintain their power.

Institutional gerrymandering can also occur in other types of political units, such as school districts. For example, a school board may redraw the boundaries of school districts to give certain neighborhoods or groups of students more resources and funding, while neglecting others.