An important consideration in this respect is whether a phrase or clause is restrictive or non-restrictive: it is restrictive if it is essential to the principal meaning of the sentence; it is non-restrictive if the principal meaning of the sentence is clear without it.
A restrictive clause introduces information that is necessary to the meaning of the sentence. A nonrestrictive clause can be removed without changing the meaning.
Restrictive clauses are usually introduced by the relative pronouns that, who, whom, or whose. A restrictive clause can have an identifying function. The astronaut who first stepped on the moon was Neil Armstrong. The restrictive clause in this sentence is who first stepped on the moon.
The type of clause determines what kind of relative pronoun to use. Generally, there are two types of relative clauses: restrictive (defining) clause and non-restrictive (non-defining) clause. In both types of clauses, the relative pronoun can function as a subject, an object, or a possessive pronoun ("whose").
restrictive modifier adds information that is not essential to our understanding of the sentence; if we remove it from the sentence, the basic meaning of the sentence does not change. A restrictive modifier identifies, or limits the reference of, the noun it modifies.
An important consideration in this respect is whether a phrase or clause is restrictive or non-restrictive: it is restrictive if it is essential to the principal meaning of the sentence; it is non-restrictive if the principal meaning of the sentence is clear without it.
There are two kinds of modifiers: nonrestrictive and restrictive. Nonrestrictive modifiers are not essential or not necessary to the meaning of a sentence while restrictive modifiers are necessary to the meaning of the sentence.
A restrictive clause introduces information that is necessary to the meaning of the sentence. A nonrestrictive clause can be removed without changing the meaning. Restrictive clauses require no punctuation; nonrestrictive clauses are usually separated from the independent clause with commas.
Restrictive clauses are usually introduced by the relative pronouns that, who, whom, or whose. A restrictive clause can have an identifying function. The astronaut who first stepped on the moon was Neil Armstrong. The restrictive clause in this sentence is who first stepped on the moon.