The disciplines that study the language are introduced: nuclear (phonetics, phonology, grammar, semantics, language of the text) the so-called branches of linguistics, where the language affects other parts of our environment (sociolinguistics, neurolinguistics ...) and the adopted diachronic, diatopic, diaphasic, diastatic approaches). Definition of "word". Grammatical study of the word: internally (morphology) and how it is combined with other units (syntax). The morphological division of the word: the morphemes. Definition and types: root, affixes; prefixes, suffixes, interfaces, infix, circumflex; inflectional morphemes and derivatives; the alterative morphemes. Other concepts: base, theme. Identification of morphemes: segmentation and recurrence; Segmentation problems in morphemes.