* Semester Hours/Credits: The most common system in the US, where one credit typically represents one hour of classroom instruction per week for a semester (usually 15 weeks). A three-credit course means three hours of class per week. This also often includes time spent on homework, readings, and studying.
* Quarter Hours/Credits: Used by some institutions, particularly in the western US. A quarter is shorter than a semester, usually around 10 weeks. The credit system is similar to semester hours but scaled to the shorter time frame.
* Credit Hours vs. Contact Hours: It's important to distinguish between credit hours (which encompass all learning activities) and contact hours (which only refer to the time spent in direct instruction, such as lectures or labs).
* Transfer Credits: Credits earned at another accredited institution can often be transferred to a new school, reducing the time needed to complete a degree. Acceptance of transfer credits varies by institution and program.
* Advanced Placement (AP) Credits: High school students can earn college credit by scoring well on AP exams.
* International Baccalaureate (IB) Credits: Similar to AP credits, but from the IB program.
* CLEP and DSST Credits: College Level Examination Program (CLEP) and DANTES Subject Standardized Tests (DSST) exams allow students to earn college credit by demonstrating competency in specific subjects.
* Experiential Learning Credits: Some institutions offer credit for relevant work experience, internships, or other practical learning experiences, through prior learning assessments or portfolio reviews.
* Portfolio Credits: Demonstrating skills and knowledge through a portfolio of work, often used in creative fields.
The specific credit requirements for a degree vary widely depending on the institution, program, and degree level (associate's, bachelor's, master's, doctoral). Always check the specific catalog or requirements of the institution and program you're interested in.