The verb tener means "to have" in Spanish. It is somewhat irregular, with changes to the stem in different forms. For example, in the yo form a g is added before the o. In other forms like tú and ellos, the e in the stem changes to ie. Tener is used to express age by saying "Tengo treinta años" instead of "I am 30 years old." It is also used with que to express obligation, like "Tengo que escribir la tarea" for "I have to write the homework."