Single-molecule fluorescence offers a versatile set of tools for the investigation of conformations and dynamics in IDPs and IDRs. FCS provides access to the diffusion time τ_diff and corresponding hydrodynamic radius R_H (see eqn 6). Single-molecule FRET provides access to the mean transfer efficiency, whereas the fluorescence lifetime provides constraints for estimating the shape of the distribution. The root-mean-square interdye distance or R_H can be used to study the coil-to-globule transition while modulating interactions (e.g. denaturant or temperature). Dependence of the interdye distance with the sequence separation between the dyes provides access to the scaling exponent. Nanosecond-FCS provides access to fast dynamics, from nanoseconds to milliseconds and enables disentangling the contribution of solvent and internal friction, either by explicitly studying the viscosity of the solution or by monitoring dynamics as function of sequence separation. Burst variance analysis (BVA) provides an alternative method to quantify slow dynamics in the microsecond to millisecond timescale. Photon trajectories provide access to kinetics of folding and binding of IDPs and transition path-times. Recurrence analysis and microfluidics enable further investigation of kinetics associated with conformational changes in different solvents or upon binding ligands. The experimental quantities can be further compared with simulations or polymer models.