A restrictive phrase or clause is essential to the meaning of a sentence. If it is eliminated, the meaning changes or becomes unclear. Restrictive phrases and clauses are not set off by commas.

A non-restrictive phrase or clause is nonessential to the meaning of a sentence. It adds extra information. The overall meaning of the sentence is not affected by its removal. Non-restrictive phrases and clauses are set off from the rest of the sentence by commas.

       I see the same woman walking to work every day. The woman, who is wearing a blue polka-dotted dress today, always looks very chic.

Enchanted Rock a pink granite mountain in the middle of Texas is actually a batholith, that was formed underground billions of years ago. Batholiths are formed by the underground cooling and solidification of magma intrusions which are the forceful movements of molten rock into existing rock formations, this process forms irregularly shaped, steep-sided rock formations. Over time, erosive and tectonic processes expose the igneous rock, (rock formed through the cooling of magma or lava,) underneath. Batholiths are areas of such exposed rock, that are at least 40 square miles in area. Most batholiths, however, are much larger and include some of the most spectacular rock formations in mountain ranges around the world, including: Half Dome and El Capitan, both in the Sierra Nevadas, Denali, the tallest North American mountain, in the Alaska Range, and, of course, Enchanted Rock in central Texas.

The Alamo is the most visited historic landmark in the state of Texas. It is located in San Antonio, on the southern end of Texas Hill Country.

The Alamo is an old Spanish mission built in the early 1700s. However, it is most remembered for the 1836 Battle of the Alamo, in which 187 men were killed by General Antonio Lopez de Santa Anna’s Mexican army.

Among those who perished at the Battle of the Alamo were Davy Crockett, frontiersman and politician; William "Buck" Travis, American lawyer and soldier; and James Bowie, Texas military commander.

Enchanted Rock, a pink granite mountain in the middle of Texas, is actually a batholith that was formed underground billions of years ago. Batholiths are formed by the underground cooling and solidification of magma intrusions, which are the forceful movements of molten rock into existing rock formations, this process forms irregularly shaped, steep-sided rock formations. Over time, erosive and tectonic processes expose the igneous rock, (rock formed through the cooling of magma or lava,) underneath. Batholiths are areas of such exposed rock that are at least 40 square miles in area. Most batholiths, however, are much larger and include some of the most spectacular rock formations in mountain ranges around the world, including: Half Dome and El Capitan, both in the Sierra Nevadas, Denali, the tallest North American mountain, in the Alaska Range, and, of course, Enchanted Rock in central Texas.