Abstract: In the ever changing environmental landscape the 21st century begins to shape, the need for dynamic and reactive electricity markets is a must. The California Independent System Operator (CAISO) is in charge of operating two distinct, yet cohesive, markets on a daytoday basis to create a functioning and dynamic electricity grid. The two markets are made up dayahead and realtime which together ensure reliability and serve load. Energy and ancillary services products are bought and sold via the CAISO markets where generators and load serving entities bid and schedule supply and demand. Additionally, with public policy mandates, new types of generation technologies are required to be part of the grid, further adding to the complexity. In this primer, a basic understanding of the intricacies of both the dayahead and realtime markets will be provided. Topics will include supply and demand, energy bid curves, historical pricing in each of the markets, how integration of renewables effect market prices, concepts of how each market is setup to operate and the future outlook on the CAISO.