Conformal field theories (CFTs) describe critical behaviour in a wide range of d-dimensional systems. In recent years much has been learned about unitary CFTs through the conformal bootstrap. However, many relevant systems are described by non-unitary CFTs with logarithmic correlation functions, known as logarithmic CFTs. In this talk I will discuss some examples of these models (e.g. critical percolation) and their observables, and explain how the bootstrap paradigm extends to logarithmic CFTs.