Abstract
The properties of paper are highly dependent on those of the natural fibres from which the sheet is made and their interaction, as determined by the structure of the sheet. The nature of the stochastic variability in paper structure is influenced by fibre properties and manufacturing process variables. The fundamentals of paper forming processes are introduced and the influence of these on structure is discussed in the context of theoretical models. Key mechanical and optical properties are described and their dependence on structure, as guided by theory, is reviewed. Throughout, the structural dependence of paper properties for satisfactory performance in end use applications is emphasised.