Purple Math has about 100 lessons covering virtually every topic in standard high school and college algebra classes. The site is divided into beginning, intermediate, and advanced levels, and a separate section is included for word problems. Purple Math excels in its use of examples; for each topic there are plenty of illustrative problems with clearly defined solutions. In addition to being an excellent resource for students, it can also be very helpful for those of us that occasionally forget some of the less often-used concepts. Everyone remember all the rules of logarithms?