Most stars form in dense compact clusters. Stars belonging to the same cluster appear to be born at the same time. According to stellar evolution models, massive stars launch powerful winds and intense radiation before any supernovae go off in the star cluster. The radiation and winds clear out the dense gas in the molecular clouds in which star clusters are born till a few Myr, but overlapping supernovae dominate after that. Compact star clusters also emit gamma rays, a tell-tale sign of cosmic ray acceleration. In the following papers we have studied the role of radiation, mechanical energy injection by stellar winds, supernovae and cosmic rays on the dispersal of the surrounding molecular cloud. We have also made mock maps in various wavebands (radio, X-ray, gamma rays) to compare with analogous observations.