Final answer:
The goal of distinguishing between restrictive and nonrestrictive phrases is to improve sentence clarity and meaning by identifying essential and nonessential information. Restrictive phrases are essential to the sentence meaning and do not use commas, while nonrestrictive phrases are supplementary and should be set off with commas.
Step-by-step explanation:
The purpose of distinguishing between restrictive and nonrestrictive phrases is to improve sentence clarity and meaning. Restrictive phrases, also known as essential information, are crucial to the meaning of a sentence and do not require commas. Nonrestrictive phrases, or nonessential information, can be removed without altering the essential meaning of the sentence and should be set off with commas. This distinction aids readers in identifying what information are necessary to understand the point being made and what is additional or supplementary.
To identify the essential information in a sentence and to determine the nonessential information in a sentence both aid in comprehension and writing effectiveness. Analyzing the structure of a sentence often involves recognizing these phrases to appreciate the writer's intent and the information's relevance to the sentence as a whole.
Placing commas around nonessential information helps ensure that the reader understands which parts of the sentence are supplemental and which are integral to the core meaning. For example, 'The labs installed 50 years ago need significant updates' contains essential information with no commas, whereas 'The labs, which were installed 50 years ago, need significant updates' includes a nonessential clause set off by commas.