Algebra 1, 2, and 3 refer to high school courses that cover different levels of algebra. Algebra 1 is typically an introductory course, while Algebra 2 serves as an intermediate level, often including more complex concepts. Algebra 3 may combine advanced topics from Algebra 2 and Trigonometry, sometimes referred to as Mathematical Analysis. In college, the equivalent course after Intermediate Algebra is called "College Algebra," with many students first taking Trigonometry. It's important to note that course titles and content can vary significantly between different schools and regions.