Book excerpt: The book addresses issues associated with physics and technology of injection lasers based on self-organized quantum dots. Fundamental and technological aspects of quantum dot edge-emitting lasers and VCSELs, their current status and future prospects are summarized and reviewed. Basic principles of QD formation using self-organization phenomena are reviewed. Structural and optical properties of self-organized QDs are considered with a number of examples in different material systems. Recent achievements in controlling the QD properties including the effects of vertical stacking, changing the matrix bandgap and the surface density of QDs are reviewed. The authors focus on the use of self-organized quantum dots in laser structures, fabrication and characterization of edge and surface emitting diode lasers, their properties and optimization with special attention paid to the relationship between structural and electronic properties of QDs and laser characteristics. The threshold and power characteristics of the state-of-the-art QD lasers are demonstrated. Issues related to the long-wavelength (1.3-mm) lasers on a GaAs substrate are also addressed and recent results on InGaAsN-based diode lasers presented for the purpose of comparison.