The academic calendar for universities in the United States typically follows a semester or quarter system, with some variations:

Semester System:

• Most universities follow a semester system, with the academic year divided into two primary terms: Fall (August/September to December) and Spring (January to May).
• Each semester is approximately 15-16 weeks long, including a final exam period.
• There is a Winter Break (around 2-3 weeks) between the Fall and Spring semesters, and a longer Summer Break (around 3 months) after the Spring semester.
• Some universities also offer a shorter Summer Session or intersession courses during the summer break.

Quarter System:

• A smaller number of universities operate on a quarter system, dividing the academic year into four terms: Fall (September to November), Winter (January to March), Spring (April to June), and Summer (July to August).
• Each quarter is typically 10-12 weeks long, including finals.
• There are shorter breaks between quarters, usually 1-2 weeks.

Other Calendar Systems:

• A few universities follow a trimester or 4-1-4 calendar, with two standard terms and a shorter optional term or break in between.
• Some institutions, especially community colleges, offer courses on a more flexible schedule, such as 8-week or 12-week terms.

It’s important to note that specific start and end dates, as well as breaks and holidays, can vary among universities and even between different programs within the same institution. Additionally, some graduate programs may follow a slightly different academic calendar than undergraduate programs.

Students should consult the academic calendar published by their respective universities to ensure they are aware of important dates, such as the start and end of classes, registration periods, and final exam schedules.