Languages have been coming and going for thousands of years, but in recent times there has been less coming and a lot more going. When the world was still populated by hunter-gatherers，small，tightly knit(联系)groups developed their own patterns of  speech independent of each other. Some language experts believe that 10,000 years ago, when the world had just five to ten million people, they spoke perhaps 12, 000 languages between them. Soon afterwards, many of those people started settling down to become farmers, and their languages too became more settled and fewer in number. In recent centuries, trade, industrialisation, the development of the nation-state and the spread of universal compulsory education, especially globalisation and better communications in the past few decades, all have caused many languages to disappear, and dominant languages such as English，

Spanish and Chinese are increasingly taking over.

At present, the world has about 6, 800 languages. The distribution of these languages is hugely uneven. The general rule is that mild zones have relatively few languages, often spoken by many people, while hot wet zones have lots, often spoken by small numbers. Europe has only around 200 languages; the Americas about 1, 000; Africa 2, 400; and Asia and the Pacific perhaps 3,200, of which Papua New Guinea alone accounts for well over 800.The median number(中位数) of speakers is mere 6,000, which that half the world's languages are spoken by fewer people than that.

Already well over 400 of the total of 6, 800 languages are close to extinction (消亡), with only a few elderly speakers left. Pick, at random, Busuu in Cameroon （ eight remaining speakers), Chiapaneco in Mexico (150), Lipan Apache in the United States (two or three) or Wadjigu in Australia (one, with a question-mark): none of these seems to have much chance of survival.

Being a blogger can be good business. Don't you believe it? Read on!

Meet Gary Vaynerchuk (GaryVaynerchuk. com)

Gary Vaynerchuk is a New Yorker who gained Internet fame because of a video blog that talked about everything related to wine. Through online video blogging, he built his wine business from a $3-million-dollar a year wine retail store to a $60-million-dollar wine wholesale business. Gary Vaynerchuk has built a multi-million-dollar empire relating to his personal brand.

Meet Rand Fishkind (moz. com)

Rand Fishkind is college dropout (辍 学 生 ) who started blogging about SEO (Search Engine Optimization) back in 2004 while working for a family-run web development company. He was also providing SEO consulting services for a few small clients. SEOmoz has left the consulting business since then and focuses on creating awesome SEO software instead. The company makes millions of dollars each month.

Meet Pat Flynn (SmartPassiveIncome. com)

Pat is one of the most inspirational bloggers in the world. After losing his job, he was forced to struggle to support his growing family. He started a website called Smart Passive Income to track his progress with various websites and online money-making- projects. He has since built massive followers and readership thanks to his honesty. Over the last 6 months, Pat has earned on average, around $50,000 per month.

Meet Andrew Sullivan (thedishdaily. com)

Andrew started his blog, The Daily Dish, near the end of 2000. By the middle of 2003, he was receiving about 300,000 unique visits per month. Just this year, Andrew made some big changes and decided to work on The Daily Dish full-time. On launch day in 2013, the blog reportedly took in over $330,000, charging $20/month per reader.

Windows are hard. They are particularly hard in northern countries like Sweden, where during winter the days are short and the sun is very low in the sky. Window design in cold climate is a technical balancing act. You want it big to get the light, but you want it small to minimize the heat loss. But there is so much more that windows have to do for our social and emotional well-being.

A recent study published in Buildings and Cities looks at the many roles that windows play and the way people use them, exploring daylight, the visual connection to the outside and the role of windows in the home during the day and night. Windows do much more than just provide light and air: "Windows represent an enjoyment of the home and fulfil much more than physical needs. They must allow sufficient personal control over fresh and cool air, sound, sunlight, street lighting and privacy. "

The study authors, Kiran Maini Gerhardsson and Thorbjorn Laike, interviewed occupants living in multi-family dwellings. Windows turned out to be very important for occupant comfort, for visual connection to the outside. But they also had to be able to be screened for privacy; sometimes these conflicted. Sometimes the sill height was important. One occupant, Dmitry was going to add some frosted film to the bottom of his window. "I don't want to see the faces of others when I'm sitting down, but when I'm standing and see their faces, I can wave to them," he said.

Interviewees preferred daylight to artificial light for many reasons, including as a time indicator, and "because it varies, increases room brightness and improves mood". Our bodies need the change from red to blue and back to red.

The authors conclude windows serve many functions that go beyond just light and air and should be designed accordingly. "There is much more to such experiences than the satisfaction of physical needs. Perceiving a room to be enough daylight, adequately pleasant and spacious seems to be equally essential, and a view of the world outside brings information to inhabit-ants. However, windows also need to prevent people outside from peering in moderate bright sunlight during the day. "