A clause is a group of words that links together two sentences into one or forms two parts of a sentence linked together by a conjunction. Clauses can be of the following types: 

1. Main clause
2. Subordinate clause
3. Conditional clause

Explaining Clause

Clauses are a group of words or phrases which consist of a finite verb and a subject in a sentence. This verb and subject are connected, i.e., express a certain relationship between them. However, a clause is not merely a group of words. It is a group of words that conveys the actions of a subject or what the subject is. The clause can often, but not always, exist as an independent sentence having some definite meaning. 

A clause can be a part of a simple or a complex sentence, and similarly, a sentence can have single or multiple clauses.

Main clause

The main clause, also known as an independent or principal clause, is a part of the sentence that can exist independently as a meaningful and complete sentence. For example,

• I love eating brownies.
• Stefan loves painting.

These are two simple sentences with independent clauses which define a noun that another cannot replace.

• The sky was clear and we could see our way.

This is a complex sentence consisting of two sentences:

• The sky was clear.
• We could see our way.

These two parts of the sentence are called clauses and are classified as main clauses as they represent a distinct sentence on their own. In other words, each sentence that can stand by itself and make perfect sense on its own can be called the main clause.

Some examples of the main clause are given below:

• She is a kind woman.
• Did you complete the work?
• I have checked all your notes.

Subordinate Clause

The subordinate clause is also known as a dependent clause. It is pretty clear from the name itself that it is known to be dependent on a sentence, i.e., it cannot make sense as a complete sentence on its own. Therefore, a subordinate clause cannot exist independently and always needs another set of words to complete it. The subordinate clause must be combined with an independent clause to form a complete sentence. 

For example: “When I grow old” is a subordinate clause. To form a complete sentence, it needs to be changed to something like this: When I grow old, I want to travel the world. In this sentence, I want to travel the world is an independent clause and stands out as a sentence on its own. 

Some examples of a subordinate clause are given below:

• When I was reading in the park, I had an epiphany.
• I know about the person who stole your bike.
• She is quite talented though she is out of practice.

Types of subordinate clauses

There are three types of subordinate clauses:

• Adjective clause
• Noun clause
• Adverbial clause

Adjective clause: A clause containing an adjective, a subject, and a predicate of its own and therefore can form a sentence when linked to other words. 

Examples:

1. I remember the place where we spent the day.
2. I am looking for the rings that I lost last night.
3. He is still up from all the coffee he drank.

Noun clause: A clause that does the work of a noun or is itself a noun but includes a subject and a predicate. 

Examples:

1. I don’t understand the rules of this game.
2. Can you guess who lost?
3. It made me angry that he went on the tour.

Adverb clause: A clause that acts as an adverb or does the work of an adverb and includes a subject and a predicate.

Examples:

1. They started the class 2 hours late.
2. He cannot see beyond a certain distance.
3. It rained as soon as we came back.

Conditional Clause

The third type, the conditional clause, is a clause that expresses a certain thing dependent on the main clause, i.e., what is being expressed by the conditional clause depends on the presence of the main clause in the sentence. Thus, the impact of the main or the principle clause depends on the subordinate clause being used.

Types of Conditional Clauses

• Zero conditional clause: In this type of conditional clause, generalised statements about actions are given with both clauses being in the present tense.

Examples:

1. If you fall down the stairs, you get hurt.
2. The milk boils if it is heated.
3. You pass the exam if you attempt all questions.

• First conditional clause: In the first conditional clause, the main clause is in the future tense, while the subordinate clause remains in the present tense.

Examples:

1. He needs to go, or he’ll be late for a meeting.
2. If he comes to the party, I’ll be very happy.
3. If I win this lottery, I’ll buy a new house.

• Second conditional clause: In this type of conditional clause, the main clause is in the simple past tense, while the subordinate clause is in the past perfect tense. It is usually used to refer to a thing in the imagination, giving advice, or asking hypothetical questions.

Examples:

1. If I went to the book fair, I would have bought at least five books.
2. If I could cook, I would make some dessert.
3. Janice would have easily passed the exams if she had ever listened in class.

• Third conditional clause: The third conditional clause has the main clause in past tense and the subordinate clause in past participle tense. These sentences are mainly used to express regret, criticism, reflecting on the past, etc.

Examples:

1. If he had been more active, he would have been healthier.
2. If she had won a gold medal, she would have continued her practice.
3. If they hadn’t spent a year on this excavation, they wouldn’t have gotten results.

Conclusion

A clause is a group of words with a subject and a predicate that can make a sentence on its own (main clause) or form a sentence when joined to the main clause (subordinate clause). The conditional clause, on the other hand, refers to the words which only make sense or form a sentence depending on the subordinate clause and the main clause.