Texas (ⁱ/ˈtɛksəs/) (Alibamu: Teksi ) is the second most populous and the second most extensive of the 50 United States, and the most extensive state of the 48 contiguous United States. The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in East Texas. Located in the South Central United States, Texas shares an international border with the Mexican states of Chihuahua, Coahuila, Nuevo León, and Tamaulipas to the south, and borders the US states of New Mexico to the west, Oklahoma to the north, Arkansas to the northeast, and Louisiana to the east. Texas has an area of 268,820 square miles (696,200 km²), and a growing population of 25.7 million residents.

During the Spanish colonial rule, the area was officially known as the Nuevo Reino de Filipinas: La Provincia de Texas. Antonio Margil de Jesús was known to be the first person to use the name in a letter to the Viceroy of Mexico in July 20, 1716. The name was not popularly used in daily speech but often appeared in legal documents until the end of the 1800s.

West Texas is a vernacular term applied to a region in the southwestern quadrant of the United States that primarily encompasses the arid and semi-arid lands in the western portion of the state of Texas.

There is a general lack of consensus regarding the boundaries that separate East Texas and West Texas.Walter Prescott Webb, the American historian and geographer, suggested that the 98th meridian separates East and West Texas. The Texas writer A.C. Greene proposed that West Texas extends west of the Brazos River. Perhaps, the truth is that there is no distinct line that separates East and West Texas. Rather, there are places that are clearly in West Texas and there are places that are clearly in East Texas, and then there are places that fall within a transitional zone between these two regions.

West Texas is often subdivided according to distinct physiographic features. The portion of West Texas that lies west of the Pecos River is often referred to as "Far West Texas" or the "Trans-Pecos," a term first introduced in 1887 by the Texas geologist Robert T. Hill. The Trans-Pecos lies within the Chihuahuan Desert, the most arid portion of the state. Another important subdivision of West Texas is the Llano Estacado, a vast region of high level plains that extends into Eastern New Mexico and the Texas Panhandle. To the east of the Llano Estacado lies the “redbed country” of the Rolling Plains and to the south of the Llano Estacado lies the Edwards Plateau. The Rolling Plains and the Edwards Plateau subregions act as transitional zones between East and West Texas.