This gigantism may have been due to higher atmospheric oxygen levels, which allowed increased respiratory efficiency. The lack of flying vertebrates could have been another factor. Many of the early groups became extinct during the PermianTriassic extinction event, the largest mass extinction in the history of the Earth, around 252 million years ago.
Different kinds of insects can be divided into groups called orders. There are many insect orders (about 29). The biggest insect orders are listed below:
All these groups except one (Odonata) are strongly connected with plants as a source of food.
Spiders, scorpions, and similar animals are not insects; they are arachnids. Arachnids are arthropods that have four pairs of legs. Centipedes are also arthropods, but not insects: they are in a subphylum called the Myriapoda.
This taxonomy lists some of the better known groups of insects.
Pests can be harmful to people in different ways. Some are parasites, such as lice and bed bugs. Some of these parasite insects can spread diseases, such as mosquitoes spreading malaria.
Other pest insects do not directly hurt people. Termites and some beetles eat wood and sometimes eat buildings, such as houses. However, termites also help break down the trees and branches that fall on the forest floor. Many insects eat agricultural products (plants meant for people to eat). Grasshoppers are one example of pest insects that eat plants in agriculture.
Some insects are useful to us. Bees make honey. The larvae of some moths make silk, which people use to make clothing. In some parts of the world, people actually eat insects. Eating insects for food is called entomophagy.
Many bees and flies pollinate plants. This means the insects help the plants make seeds by moving pollen from one flower to another. Some good insects eat pest insects, such as lady beetles (or ladybirds or ladybugs) eating aphids. Many insects eat dead plants and animals.
People often use poisons called insecticides to kill pest insects. Insecticides do not always work. Sometimes the pest insects become resistant to the insecticides, which means the insecticides do not hurt them anymore. Both the Colorado potato beetle and the diamondback moth are insects that are resistant to many insecticides.
Insecticides do not only kill pest insects; sometimes many helpful insects are killed too. When helpful insects are killed, such as those that eat pest insects, the pest insects may come back in larger numbers than before because they are not being eaten by helpful insects anymore.
List of operating systems
This is a list of operating systems.
Operating systems written for a hobby.
Little operating systems that run on small devices.
Operating systems that have only appeared in fiction or as jokes.
Computer jargon
Computer jargon means words to do with computers and surrounding topics. Knowing what these words mean can help people know more about computers. Most people use these words to discuss computer ideas, but some people use these words to impress others (also known as buzzwords).
Some examples of jargon are:
Million
One million (1,000,000), or one thousand thousand, is the natural number after 999,999 and before 1,000,001. The name is derived from Italian, where was 1,000, and 1,000,000 became a ""milione"", as 'a large thousand'.
In scientific notation, the number is written as 1×10 or just 10. Physical quantities can also be expressed using the SI prefix when dealing with SI units. For example, 1 megawatt equals 1,000,000 watts.
The word 'million' is common to both the short-scale and long-scale numbering systems, unlike the larger numbers, which have different names in the two systems.
The million is sometimes used in the English language as a metaphor for a very large number, as in 'Never in a million years' and 'You're one in a million', or as hyperbole, as in 'I've walked a million miles'.
"Il Milione" is the title of Marco Polo's narration of his travels in China. The name is supposed to come from Polo's nickname after his tales of riches and multitudes.
1000 (number)
A thousand (1000, one thousand or 1,000) is the natural number after 999 and before 1001. One thousand thousands is known as a million.
In Roman numerals, 1000 is written as M.
Gross domestic product
In economics, gross domestic product (GDP) is how much a place produces in an amount of time. GDP can be calculated by adding up its output inside the borders of that country.
To find the GDP of a country, one adds up all consumer spending (C), all investment (I), all government spending minus taxes (G), and the value of exports minus imports ("X – M"). This is shown by the equation:formula_1 This measure is often used to find out how healthy a country is; a country with a high value of GDP can be called a large economy. The United States has the largest GDP in the world. Germany has the largest in Europe, Nigeria in Africa and China in Asia.
There are different ways to calculate the GDP. Nominal GDP is the total amount of money spent on all new and final goods in an economy, real GDP (adjusting for changes in prices) tries to correct this number for inflation. For example, if the prices rise by 2% (meaning, everything costs 2% more) and the nominal GDP grows by 5%, the real GDP growth is only increased by 3%.
GDP per capita is the total income of a country, divided by the number of inhabitants. It shows how rich people, on average, are.
The GDP measure is different from gross national product (GNP) in that GNP = GDP + net income from assets in other countries (net income receipts).
When the gross domestic product is evaluated at the current market prices, it is called the nominal GDP. It includes changes in prices which makes it different from the real GDP. These changes can be due to inflation or price fluctuations. It can be measured in one of three different ways. The "income approach" uses the total of all income from businesses and individuals in a single year. The "expenditure approach" uses the market value of all goods purchased in a single year. The "production approach" is based on the total production in a single year.
Cricket
Cricket is a sport which is played between two teams of eleven players each. One team, which is batting, tries to score runs , while the other team is fielding, and tries to prevent this. Runs are scored by hitting the ball, which is thrown by a player from the fielding team to a player from the batting team, across the boundary, or by the batting team's players running between two areas of the field called the batsmen's grounds as many times as possible before the fielding team successfully hits a wicket (set of sticks) in either of the grounds with the ball to get them out.
The wickets are sets of three small, wooden posts that are at each end of a rectangle of short grass called 'the pitch', which is 22 yards long. The pitch is inside a much larger oval of grass called the 'area of play'. The area of play is a 30 yard circle inside the cricket ground or stadium. When a player is out, a teammate will replace them in the field. When a team no longer has enough "not-out" players left to score, then the other team gets the chance to try to score. In shorter games of cricket, a team may also have to stop batting when the ball has been thrown to their players a certain number of times. After both teams have had enough chances to score, the team with the most runs wins.
The game started in England in the 16th century. The earliest definite reference to the sport is in a court case of 1598. The court in Guildford heard a coroner, John Derrick, that when he was a scholar at the "Free School at Guildford", fifty years earlier, "he and diverse of his fellows did run and play [on the common land] at cricket and other players". Later, the game spread to countries of the British Empire in the 19th and 20th centuries.