The epithelial-mesenchymal (E/M) hybrid state has emerged as an important mediator of the elements of cancer progression facilitated by epithelial mesenchymal plasticity (EMP). We review here the evidence for the presence and prognostic potential of E/M hybrid state in carcinoma, modelling predictions and validations studies to demonstrate stabilised E/M hybrid intermediates along the spectrum of EMP, and computational approaches for characterising and quantifying EMP phenotypes, with particular attention to the emerging realm of single-cell approaches through RNA sequencing and protein-based approaches.