Barter is a system of exchange where goods or services are directly exchanged for other goods or services without using a medium of exchange, such as money. It is distinguishable from gift economies in many ways; one of them is that the reciprocal exchange is immediate and not delayed in time. he definition of barter is a system under which goods and services are exchanged instead of currency, or the actual goods or services that are being exchanged. An example of barter is when the people within a community exchange goods and services so that money needn't be used.

Heat zones are the different zones of the earth, where the sun's rays fall differently, thus causing different climate patterns. These zones are called the Torrid Zone, the two Temperate Zones, and the two Frigid Zones. The Torrid Zone is very hot since the sun shines overhead here. The Temperate Zones maintain a moderate climate, and the Frigid Zones are extremely cold. 

Solar system refers to the family of sun. The sun, the nine planets, the satellites and other celestial bodies such as asteroids and meteoroids forms the solar system

History can be generally defined as the past, and how past relates to the human lives. The main difference between history and prehistory is the existence of records; history is the recorded events of the past whereas Prehistory is the time before writing was introduced. Therefore, it is clear that prehistory, as the name suggests, is the time period before history.

According to the standard Big Bang model, the universe was born during a period of inflation that began about 13.8 billion years ago. Like a rapidly expanding balloon, it swelled from a size smaller than an electron to nearly its current size within a tiny fraction of a second. Our universe began with an explosion of space itself - the Big Bang. Starting from extremely high density and temperature, space expanded, the universe cooled, and the simplest elements formed. Gravity gradually drew matter together to form the first stars and the first galaxies. The best-supported theory of our universe's origin centers on an event known as the big bang. This theory was born of the observation that other galaxies are moving away from our own at great speed in all directions, as if they had all been propelled by an ancient explosive force.

The Paleolithic was an age of purely hunting and gathering, but toward the Mesolithic period the development of agriculture contributed to the rise of permanent settlements. The later Neolithic period is distinguished by the domestication of plants and animals. Divided into three periods: Paleolithic (or Old Stone Age), Mesolithic (or Middle Stone Age), and Neolithic (or New Stone Age), this era is marked by the use of tools by our early human ancestors (who evolved around 300,000 B.C.) and the eventual transformation from a culture of hunting and gathering to farming and food production. During this era, early humans shared the planet with a number of now-extinct hominin relatives, including Neanderthals and Denisovans.

A globe is a perfect representation of the Earth because -

•     A globe represents the three-dimensional view if the Earth.
•     It shows the shape of the Oceans and the Continents correctly.
•     It shows their correct relation to one another as they are on the Earth.
•     A globe helps us to understand how day and night occur and how seasons are called.

A December 2017 report stated that 3.465-billion-year-old Australian Apex chert rocks once contained microorganisms, the earliest direct evidence of life on Earth. A 2013 publication announced the discovery of microbial mat fossils in 3.48 billion-year-old sandstone in Western Australia. Something profound happens when astronauts see Earth from space for the first time. Seeing planet Earth from space can cause a shift in awareness, according to NASA astronauts. This state of mental clarity is known as the "overview effect," in which the viewer becomes overwhelmed and awed by the size of Earth.

Ladakh is a cold desert in India. It lies in the Great Himalayas, on the eastern side of Jammu and Kashmir. It has the mighty Karakoram Range in the North and in the south, it is bound by the  Zanskar mountains. Several rivers flow through Ladakh. The most important one is the Indus.

These rivers form deep valleys and gorges. They add to the scenic beauty of the place. Several glaciers are found in Ladakh. The Gangotri glacier is an example. The altitude in Ladakh varies from about 3000m in Kargil to more than 8000 m in the Karakoram.

The desert type of climate is typical of Leh Ladakh with dry winds blowing throughout the day and summers being hot and humid. On your visit to Leh, you will face the colddesert climate, especially from October to March. In winters the temperatures are extreme in Leh, dipping below freezing point. Ladakh is called the Cold Desert. Desert lands with extremely low temperatures are called cold deserts like Antarctica, which is the largest cold desert in the world. Ladakh in India is a cold desert that lies in the Great Himalayas on the eastern side of Jammu and Kashmir.

Sulaiman and Kirthar hills are to the north-west of India; About 8000 years ago, men and women first began to grow crops of wheat and barley.

Cooked rice refers to rice that has been cooked either by steaming or boiling. The terms steamed rice or boiled rice are also commonly used. Any variant of Asian rice (both Indica and Japonica varieties), African rice or wild rice, glutinous or non-glutinous, long-, medium-, or short-grain, of any colour, can be used. Rice for cooking can be whole grain or milled.

Cooked rice is used as a base for various fried rice dishes (e.g. chǎofàn, khao phat), rice bowls/plates (e.g. bibimbap, chazuke, curry rice, dal bhat, donburi, loco moco, panta bhat, rice and beans, rice and gravy), rice porridges (e.g. congee, juk), rice balls/rolls 

Mohenjodaro had the Great Bath, a watertight tank layered with natural tar. Kalibangan and Lothal had fire altars, where sacrifices may have been performed. And some cities like Mohenjodaro, Harappa, and Lothal had elaborate storehouses

When someone acts on the basis of prejudices, the act may result in discrimination. Debarring someone from certain facilities only because of difference in religion, gender, caste or regional origins is called discrimination. Following are some examples of discrimination:

Gender-based Discrimination: A girl is not allowed to go to school beyond standard five or six is an example of discrimination. Similarly, most of the girls are not allowed to select a career of their choice rather they are forced into marriage. In some families, girls are not allowed to wear western dresses while boys in such families often wear western dresses.

Religion-based Discrimination: A person does not get a job only because he belongs to a particular religion. A person is not allowed to enter some public places; especially the places of worship; because he/she belongs to another religion.

Caste-based Discrimination: Caste system is an age-old system in India. According to this system, people were kept under different castes. A person from a particular caste was supposed to do only a particular kind of work. For example; a person from Mahar caste could only engage in cleaning the garbage and clearing dead carcasses from the village. In spite of getting education and developing skills, people could not change their occupation.

The word celestial is primarily used to describe things that have to do with the heavens such as angels, spirits, stars and planets. It does not come from words meaning God or soul though, but from the Latin word for sky caelestis, which also gave rise to the word ceiling. Most of the religions of the world are teaching us about some celestial divine beings. The term Celestial Being means a creature from the sky and it usually refers to angels. God created them as light beings. They are very powerful angels who are helping and guiding humanity.

There are essentially three types of Earth orbits: high Earth orbit, medium Earth orbit, and low Earth orbit. Many weather and some communications satellites tend to have a high Earth orbit, farthest away from the surface. It is important to understand the difference between rotations and revolutions. When an object turns around an internal axis (like the Earth turns around its axis) it is called a rotation. When an object circles an external axis (like the Earth circles the sun) it is called a revolution. There are two types of orbits: closed (periodic) orbits, and open (escape) orbits. Circular and elliptical orbits are closed.

The north star indicates the north direction. It is also called the pole star. It always remains in the same position in the sky

Celestial Bodies: The sun, the moon, planets, stars and other bodies in the universe are called celestial bodies.

Paleolithic Period or Old Stone Age; the earliest period of human development, last until approx 8000 BC. The Paleolithic Period is divided into two eras: the Lower Paleolithic (to 40,000 BC) and the Upper Paleolithic (40,000–8000 BC). During the Paleolithic, hominins grouped together in small societies such as bands, and subsisted by gathering plants and fishing, hunting or scavenging wild animals. The Paleolithic is characterized by the use of knapped stone tools, although at the time humans also used wood and bone tools.

History (from the Greek ἱστορία, meaning ‘a learning or knowing by inquiry’) can be broadly taken to indicate the past in general but is usually defined as the study of the past from the point at which there were written sources onwards.
There are obstacles that make it so we do not have a crystal clear, uninterrupted view of the past. Firstly, we have to remember that everyone – not just us, but also people throughout history – is shaped by their upbringing and the societies and times they live in, and we need to be careful not to stick our own labels and values onto past periods. Secondly, our view of the past is made up from the total of things that somehow happened to survive the test of time, which is due to coincidences and decisions made by people before our time. So, we only get a fragmentary, distorted view; it is like trying to complete a puzzle with a lot of oddly shaped and missing pieces.

• Drained by the Ganges and the Son rivers, Magadha became the most powerful mahajanapada in ancient India.
• Magadha was important for transport and trade, and its fertile regions made agriculture prosper. Parts of Magadha were forested and elephants from there were trained to fight for the army.
• Forests also provided wood, and the iron mines in the region provided the metal to make strong weapons and tools.
• Magadha had many powerful rulers such as Bimbisara and Ajatsatru of the Haryanka dynasty, and Mahapadma Nanda of the Nanda dynasty.

Archaeology is the study of the ancient and recent human past through material remains. 

Archaeology is the science that studies human cultures through the recovery, documentation, analysis and interpretation of material remains and environmental data, including architecture, artifacts, features, biofacts and landscapes.