While direct object pronouns answer the question what? or whom? Indirect object pronouns answer the question to whom? or for whom? Also, they're the same as the Direct Object Pronouns except for the pronouns in the Third Person (i.e. to him; to her; to them).
|mi||(to/for) me||ci||(to/for) us|
|ti||(to/for) you (informal)||vi||(to/for) you (informal)|
|gli||(to/for) him, it||loro||(to/for) them (m. & f.)|
|le||(to/for) her, it|
|Le||(to/for) you (formal f. & m.)||Loro||(to/for) you (formal f. & m.)|
The direct object is governed directly by the verb, for example, in the following statement: Romeo loved her.
The Indirect Object in an English sentence often stands where you would expect the direct object but common sense will tell you that the direct object is later in the sentence, e.g.: Romeo bought her a bunch of flowers.
The direct object — i.e. the thing that Romeo bought is “a bunch of flowers”; Romeo didn't buy “her” as if she were a slave. So the pronoun her in the sentence actually means "for her" and is the Indirect Object.