Chlorophyll alpha fluorescence has become a routine method for obtaining information on various aspects of photosynthesis. The terms and definitions are sometimes used convertibly, which became a source of misunderstanding. In this article, the most accepted viewpoint is presented on chlorophyll fluorescence meaning in monitoring and characterising of photosynthetic events. It was exemplified that strawberry shoot cultures show photosynthetic activity through multiplication subculture. Light and dark phases of photosynthesis function better when glucose is added to the medium in comparison to sucrose-medium. Photosynthetic efficiency of acclimated plantlets is higher than that of cultured shoots, but it is far from full activity of plants growing in natural conditions. The leaves formed during in vitro life slowly decrease, but newly formed leaves acquire the photosynthetic activity at the time of acclimatisation.