In Persian a direct object is marked with the post positioned particle rā را. This rā is applied to a noun, which is specific and definite. Compare and contrast the following sentences:

از کتابفروشی کتاب خریدم
az ketābforuši ketāb xaridam
“I bought (a/some) book from (a/the/some) book store.”

از کتابفروشی کتاب را خریدم
az ketābforuši ketāb rā xaridam
“I bought the book from (a/the/some) book store.”

Proper nouns, pronouns (including the demonstrative pronouns), and nouns which are modified by a demonstrative adjective or by possessive construction, are all construed as specific and take rā:

The mere specificity of a noun does not necessarily call for the direct object marker. A specific noun may be a direct or an indirect object of the sentence. Compare and contrast the following two sentences:

مادر حسن را دیدم
mādar-e hasan rā didam
“I saw Hasan’s mother.”

به مادر حسن قوری را پس دادم
be mādar-e hasan quri rā pas dādam
“I gave the tea-pot back to Hasan’s mother.”

In Persian, if there is more than one object in the sentence, normally one object or a group of objects is the indirect recipient of the action (dative), and the other is the direct receiver (accusative). There is no particular order:

آن کتاب را به آن مرد دادم
ān ketāb rā be ān mard dādam
“I gave that book to that man.”

به آن مرد آن کتاب را دادم
be ān mard ān ketāb rā dādam
“I gave that book to that man.”

If there is more than one object, normally linked by the coordinators, one group is still the direct object, and the other the indirect object, of the sentence:

آن کتاب٬ دفتر و مداد را به آن دانشجو دادم
ān ketāb-o daftar-o medād rā be ān dānešju dādam
“I gave that book, notebook, and pencil to that (college) student.”

آن کتاب٬ دفتر و مداد را به آن دختر و پسر دانشجو دادم
ān ketāb-o daftar-o medād rā be ān doxtar-o pesar-e dānešju dādam
“I gave that book, notebook, and pencil to those (college) students, the boy and the girl.”

In Persian, an indirect object is always preceded by a preposition, while a direct object, although it does not take a preposition, may or may not take the direct object marker rā:

The direct object marker rā always follows the object, or the object and its attributes, the adjectival and genitival segments (ezāfe construction) immediately:

If the sentence has more than one object, and the objects are linked with the coordinator va, ‘and,’ or its substitutes, the comma and the enclitic [-o-], rā only follows the entire chain:

آن مرد و زن و بچّه‌شان را دیدم
ān mard-o-zan va bačče-šān rā didam
“I bought the book.”

آن کتاب٬ دفتر٬ مداد و قلم را خریدم
ān ketāb, daftar, medād va qalam rā xaridam
“I bought that book, notebook, pencil, and pen.”

But if the elaboration on the object is separated by a conjunction, then the rā precedes the conjunction:

کتابی را که ‌گفتید٬ خریدم
ketābi rā ke goftid xaridam
“I bought the book that you said.”

NEVER:

کتابی که ‌گفتید را خریدم
ketābi ke goftid rā xaridam

آن کتاب خوب آن نویسنده را که می‌گفتید خریدم
ān ketāb-e xub-e ān nevisande rā ke mi goftid xaridam
“I bought that good book by the author that you were talking about.”

NEVER:

آن کتاب خوب آن نویسنده که می‌گفتید را خریدم
ān ketāb-e xub-e ān nevisande ke mi goftid rā xaridam

The personal pronouns من man and تو to followed by را rā may be contracted as مرا marā and ترا torā:

من را/مرا نگاه کنید
marā negāh konid
“Look at me!”

تو را/ترا دیدم
torā didam
“I saw you.”

It must be understood that more than anything, using the را rā depends on the specific verb. Some verbs take a direct object and some an indirect object. For instance, verbs which have to do with the five senses take a direct object, hence, the rā is used:

Verbs of affection also take direct objects:

Verbs expressing aggression also take direct objects:

Normally the indefinite noun does not take the را rā. However, if that noun is specific and particular (as in “a certain thing”), then it takes the rā:

در تاریکی گربه ای دیدم
dar tāriki gorbe-yi didam
“I saw a cat in the dark.”

در تاریکی گربه ای را دیدم
dar tāriki gorbe-yi rā didam
“I saw a particular/certain cat in the dark.”

Since the main verb of the sentence always agrees with the subject, in dependant clauses, if there is an object in the subordinate clause, it may or may not take the را rā, depending on the verbal agreement:

مردی را که می‌شناسم دیدید؟
mardi rā ke mi šenāsam didid?
“Did you see the man whom I know?”

مردی که می‌شناسم آمد
mardi ke mi šenāsam āmad
“The man whom I know, came.”

In the second sentence, the entire مردی که می‌شناسم mardi ke mišenāsam ‘the man whom I know,’ as a whole, is the subject of the sentence.

نامه ای را که دیروز نوشتم٬ فرستادید؟
nāme-yi rā ke diruz neveštam, ferestādid?
“Did you send the letter which I wrote yesterday?”

نامه ای که دیروز نوشتم٬ کجاست؟
nāme-yi ke diruz neveštam, kojāst?
“Where is the letter which I wrote yesterday?”

In the first two sentences the verbs فرستادید ferestādid and چه کردید ce kardid agree with the person who the speaker is addressing, while in the second sentence the verb –st (< ast) ‘is’ agrees with the letter as the subject and not the object of the sentence.