Electron cloud effects is an academic concept within accelerator physics that describes the collective phenomena arising from the interaction between a circulating charged particle beam and a cloud of low-energy electrons accumulated within the vacuum chamber. This research area investigates the mechanisms of electron generation (such as ionization and secondary emission), the dynamics of the electron cloud, and its detrimental impact on beam properties including stability, emittance, and lifetime, which is of significant importance for the design and operation of high-intensity particle accelerators.