Spanish uses less possessives and possessive structures in general than English does. It does use them in obvious cases, that is, when the possessor is relevant, or when the sentence doesn’t feel complete otherwise. For example:
Most of the times, when you use a possessive in English, Spanish will use one as well. However, there are several exceptions, which we’ll try to sum up. These are your rules of thumb.
No possessive with body parts
Normally, Spanish will not use possessives when body parts are involved. Look at the following example:
Most English speakers learning Spanish would incorrectly say something like
that is, a direct translation of the English sentence. But please don’t.
For the Spanish mind, if a head is hurting, it must be your own head, so a possessive is redundant. Instead, Spanish makes use of a “dative” pronoun (me in the example above), and the noun (i.e. the body part) is premodified by the definite article.
You may find possessives with body parts in sport media, as in this example:
This is a bad habit that sport journalists have for some mysterious reason, and it’s often criticized by people concerned about the language.
No possessive for middle voice
Now we are getting serious. By “middle voice” we’ll understand that the subject-agent of the action has a special interest in that action. Ancient Greek, for example, had its own set of inflexions for the middle voice. English, however, expresses the middle voice with, again, a possessive:
In the above examples, you don’t actually possess the cereal nor the homework. In the third example, you know about comics in general (whether you possess some or not). This is middle voice (along with other things that are irrelevant in this article).
In Spanish, again, a possessive is not used, but, again, a “dative” pronoun, or even no special mark:
Whether the “dative” pronoun should be used or not is a matter of ear, so keep learning and paying attention!