Tutorial on 'Explainability for NLP' given at the first ALPS (Advanced Language Processing) winter school: http://lig-alps.imag.fr/index.php/schedule/ The talk introduces the concepts of 'model understanding' as well as 'decision understanding' and provides examples of approaches from the areas of fact checking and text classification. Exercises to go with the tutorial are available here: https://github.com/copenlu/ALPS_2021