This paper presents an approach (from the point of view of the Text Grammar of Spanish language, i.e. the grammar that considers the text as the highest unity of analysis) to some particles that the Spanish grammatical tradition has hardly paid attention to. We talk about the expressions: por ejemplo, así, como, ejemplo, verbigracia, a saber and esto es, which we have named text markers of "exemplification", taking into account the textual function that they play or can play. Although we can find many other expressions that fulfil this function, the forms we have pointed out above are the only ones that are lexicalized and, therefore, susceptible to a grammatical study. The principal aim of the paper is to give a formal and functional description of the aforementioned markers in the grammatical system of Spanish language; in order to do that, we have analyzed a wide corpus of written and oral language.