This paper is intended to present the main features of our approach, at different stages, to the study of pool and wall fires during the past 20 years in Poitiers. The main experimental, theoretical and numerical approaches developed to obtain a proper evaluation of the different transports sustaining the burning phenomena are presented here. First, the combustion of a horizontal solid in a gaseous stream flowing parallel to its surface is presented. Then, a vertical burning wall is investigated. The structure of the reaction flows was studied in parallel, using simulation burners or water-cooled porous wall burners. The last part of the paper is related to the influence of gravity on wall and pool fires, and of cross-wind on the structure of the diffusion flames, and to phenomena involved in the generation and movement of smoke and in liquid pool fires producing boilover. Special emphasis has been given to the evaluation of convective and radiative transports.