A thorough knowledge of bubble dynamics and its influence on bed behaviour and heat transfer is essential for optimum design and control of fluidized bed reactors in general and fluidized bed combustors in particular. Recent developments in the field of on-line statistical analysis of bed pressure fluctuations to study bubble and bed dynamics are emphasized with a view to highlight its potential as a research and control technique. Bubble characteristics based on the modified two phase theory for small and large particles are summarized. Particle classification schemes are discussed to bring out the potential of Archimedes number as criterion. The progress achieved in modelling heat transfer in large particle beds is assessed.