The purpose of Esp. self module 1 is to provide you with the basic learning skills which will lead you to understand technical and scientific texts. A prefix can be a letter or group of letters that may be added to the beginning of a word. word in order to modify its meaning. Suffixes are used at the end of words in order to change the Word to fit grammatically within a sentence. The assignments are just to help you understand in a better manner the prefixes and suffixes.