Columbus landed on a small island in the Bahamas on 12 October, 1492 

Columbus called the people he met "Indios" in the belief that he was in India

Though the term "Indian" has stuck, these people all had names for themselves: they were the Abnaki, the Kwakiutl, the Lakota, the Hualapai, the Yana, and the Ani-Yunwiya (later to be known as the Cherokee), just to name a few. 

All "Indians" are not the same.

At the time of the European encounter with the native American civilizations 

 40 million - 75 million people living in the Western Hemisphere

Great Variation in Life ways 

• gathering and hunting societies

• small-scale farming societies

•  urban based civilizations (Teotihuacan was bigger than any city in Europe)

Some groups were sedentary, e.g. Mandan, spent their lives in one place, tilling the soil

others, were transhumant, e.g. Yokuts of California's San Joaquin Valley, lived part of the time in villages, leaving them only for seasonal activities; 

others were nomadic, like the Paiute of Nevada, led a nomadic life-style involving a fairly constant pattern of group movement throughout the year gathering wild plants & hunting game.

Languages

perhaps as many as 400 different languages were spoken in what is now the U.S., Canada, and northern Mexico. 

     big version

And in one area, California, at least 90 separate languages were spoken--some as similar as Spanish and Portuguese, others as dissimilar as English and Vietnamese.

Your book says that there were as many as 2200 different languages in N and S America, some 550 to 650 of which were in use in Central and North America at the time of Columbian contact. The exact number will never be known.

Many of these languages have become extinct. Go here for list of living languages

Physical characteristics 

Some populations were tall - e.g. the Mojave and Yuma

Others were typically short and stocky -ve.g. the Yuki of northwestern California

Some looked like the Indian on the old buffalo nickel, with hawk like noses and high cheekbones, such as found among present day Lakota Sioux.

Others had flat noses and round faces, reminiscent of present-day Asian populations.

Roots

Anthropologists claim that before about 15,000 years ago their ancestors entered northwestern North America by way of a land bridge that connected western Alaska with northeastern Siberia. 

Beringia Land Bridge

What evidence is there that people in the new world came to be there via a land bridge? 

These First Americans hunted large game animals, gathered vegetable foods, trapped small game, perhaps took fish and shellfish, and lived in small family groups. 

Then, about 8-10,000 years ago, the herd animals the people had depended upon became extinct and new life ways emerged. People began to exploit a much wider array of foods, especially plants and small game. Eventually grinding stones were invented and allowed people to process seeds, nuts, and other plant products. This life way lasted in many parts of North America until after the arrival of Europeans.

In other areas gathering and hunting was augmented by cultivation of plants, allowing people to become more sedentary. In the southwestern U.S. and northwestern Mexico, some gathering and hunting societies also took up farming about 2000 years ago, leading to the Hohokam and Anasazi cultural traditions, the latter considered to be one of the high-water mark civilizations north of Mexico.

In the eastern U.S. people became farmers about 4,500 years ago when they domesticated the sunflower, squash, sumpweed, & amaranth. From these societies arose a sequence of mound building cultures, including the Adena & Hopewell. These societies are knows for their elaborate mound burials, long-distance trade in raw materials, and skill as craftspersons. 

Several thousands of years later maize (corn) and beans were added, resulting in the climax cultures of this area, participants in the Mississippian tradition. Concentrated in the valleys of the Mississippi River and its main tributaries, Mississippian societies built large towns and cities, erected elaborate terraced temple mounds, created a well-developed calendrical system, and engaged in wars of territorial conquest.

However, before this diversity could be observed, recorded, and appreciated, it had largely disappeared. The arrival of the Europeans brought unprecedented change, havoc, and death. Armed with the ethnocentric view that European cultures, values, lifeways, abilities, achievements, and religion were more advanced, were better than anything the Indians had, the Europeans seized the native peoples' lands and resources, destroyed their societies and cultures. Coupled with this was the spread of European diseases which decimated the Native American population. By the seventeenth century, more than fifty million native of North and South America had died as a result of war, enslavement, and disease in what may have been, in the words of the historian Alvin Josephy, "history's greatest holocaust by far."

Over the next three centuries the Native People of North America struggled against the virulent racism, patronization, condescension, and policies of forced assimilation--the determination to stamp out Indianness--by the ever-expanding European based societies. At the beginning of the twentieth century, the Indian population in North America had dropped to an all-time low of some 250,000 - 350,000 people, most of whom were living (and dying) on reservations as little more than political prisoners. Denied freedom of religion, the right to govern themselves and manage their own affairs, and having their Indianness literally beaten out of them by all manner of prohibitions and punishments, they nevertheless persisted.

Despite the statistics showing that present day Native Americans are among the most disadvantaged populations in terms of health, education, unemployment rates, and income levels; and despite the continuing activities on the part of the U.S. government to cut most social and welfare services on Indian reservations, the Native Americans are surviving and their U.S. and Canadian populations are on the rise. Pride in Native American heritage has survived as well. On many reservations, tribal languages and religious ceremonies are enjoying renewed vigor, traditional arts and crafts continue to be practiced, some contemporary Native American artists of North America have successfully adapted European styles to their paintings and prints of Native American subjects, and the strength of the Native American narrative tradition can be felt in the poetry and novels of the many Native American writers.