Breakdown of Puedes invitar a quien quieras.
a
personal a (marks a person object)
invitar
to invite
querer
to want; to love (a person)
poder
to be able to
Questions & Answers about Puedes invitar a quien quieras.
Why do we need the word a before quien here?
This is the personal a. Even though we do not know the specific identity of the person yet, the verb invitar (to invite) takes a person as its direct object. In Spanish, whenever a person is the direct object of a verb, you must put an a before them, including before relative pronouns like quien.
Why is quieras in the subjunctive rather than the indicative (quieres)?
The subjunctive quieras is used because the person being invited is indefinite or unknown to the speaker at this moment. You are saying whoever that might be rather than referring to a specific, known person. If you used the indicative quieres, it would mean you can invite the specific person you already have in mind.
Could I use quienquiera que instead of just quien to mean whoever?
Yes, you could say Puedes invitar a quienquiera que quieras. However, simply using quien followed by a verb in the subjunctive is a very natural and common way to express whoever in everyday Spanish, making the longer phrase quienquiera que unnecessary here.
Why is it quien (singular) if I might want to invite multiple people?
Quien is often used as a general, neutral whoever regardless of the exact number. However, if you specifically want to emphasize that the listener can invite several people, you can use the plural form and say Puedes invitar a quienes quieras.