This text describes in detail the many numerical techniques and algorithms that are part of modern circuit simulation packages, with an emphasis on the most typically used simulation mode, namely transient analysis. The material is clearly presented, rigorously explained, and sufficient detail is presented to enable the reader to write his/her own circuit simulator. Given how few textbooks are in print on circuit simulation, this text should be a welcome addition to the shelves of many design engineers and computer-aided design practitioners, as well as a graduate-level text.