Cursives are used to make emphasis within a text. For instance, a textbook may use boldface and cursive typefaces to remark important words or words that are being defined. The same applies for essays.
They are also used to write foreign words that are not proper names ('extranjerismos').
They are also used for writing scientific names (biology) and technical names, e.g. Felix Leo, cannis familiaris, blue-ray
They are also used for writing the names of paintings, books, compositions, songs, prducts, etc, specially if their names are written in a foreign language within a text in Spanish (however conventions may vary on this regard), eg. Nabucco, Rigoletto, Bal au Moulin de la Galette,
