Summary: Higher categories are motivated by many areas of maths, from axiomatisation of QFTs to homological algebra or the category of spectra, and they exploit the combinatoriality of the category of simplices (Δ) to manage the vast amounts of homotopy coherence data that higher categories require. This talk introduces some of the motivation, intuition and key concepts (simplicial sets, horns, and the horn filling condition) needed to define (∞, 1)-categories as in the quasicategory model.