If the verb in the predicate is transitive, it must have an object to complete its meaning. Consider the sentence ‘The cat killed the mouse’. The words ‘the cat killed’ by themselves do not make complete sense. But the sentence ‘The cat killed the mouse’ expresses a complete thought. Here ‘the mouse’ is the object of the verb killed.

Kinds of object

The object word is always a noun or a noun-equivalent.

• We bought a car. (Here the object is the noun car)
• They built a house. (Noun)
• The boy killed the spider. (Noun)
• The police caught the thief. (Noun)
• We all respected him. (Pronoun)
• She loves singing. (Gerund)
• The thief tried to escape. (To-infinitive)

Direct and indirect objects

• I bought him a present.
• She gave me a pen.

In sentence 1, present is the direct object of bought and him is the indirect object.

I bought …what? A present (direct object)
I bought …to whom? Him (indirect object)

Similarly in sentence 2, pen is the direct object and me is the indirect object of gave.

Notes

The indirect object usually refers to a person and the direct object usually refers to a thing.

Related posts:

1. Transitive and intransitive verbs
2. Active and Passive Voice
3. Intransitive verbs used as transitives
4. What are Relative Pronouns and What Do They Do?