These crawls are part of an effort to archive pages as they are created and archive the pages that they refer to. That way, as the pages that are referenced are changed or taken from the web, a link to the version that was live when the page was written will be preserved.Then the Internet Archive hopes that references to these archived pages will be put in place of a link that would be otherwise be broken, or a companion link to allow people to see what was originally intended by a page's authors.The goal is to fix all broken links on the web . Crawls of supported "No More 404" sites. ||||| Image copyright Science Photo Library Image caption The house dust contained 2,000 types of fungi - including Aspergillus shown here 
 
 The dust in our homes contains an average of 9,000 different species of microbes, a study suggests. 
 
 Researchers from the University of Colorado at Boulder analysed the dust found in 1,200 households across the United States. 
 
 They discovered that the types of bacteria and fungi varied depending on where the home was located, who lived there and whether pets were present. 
 
 The research is published in the Proceedings of the Royal Society B. 
 
 This is really basic natural history we are investigating here Dr Noah Fierer, University of Colorado at Boulder 
 
 Dr Noah Fierer, associate professor of ecology and evolutionary biology, who carried out the study, said: "This is really basic natural history we are investigating here. 
 
 "We have known for a long time that microbes live in our homes. What we are doing is now is old-fashioned science, to see how they vary across space." 
 
 The study is part of a citizen science project called The Wild Life of Our Homes. 
 
 Image copyright Anne Madden/Robin Hacker-Cary Image caption The scientists were sent house dust samples from 1,200 homes across the United States 
 
 Volunteers from 1,200 homes across the United States sent dust samples to the researchers. 
 
 They scooped up the detritus from the ledges above doorways - a spot, the scientists say, that is often overlooked while cleaning. 
 
 A genetic analysis of the house dust revealed a menagerie of microscopic creatures. 
 
 The researchers found that the average household had more than 2,000 different types of fungi. 
 
 These included well-known moulds such as Aspergillus, Penicillium, Alternaria and Fusarium. 
 
 However, the exact make-up of the fungal ecosystem depended on the home's location. 
 
 "Most of the fungi we are seeing in the home appears to be coming from outside the home," said Dr Fierer. 
 
 "They enter the home on our clothing, or through open windows or through doors. 
 
 "Therefore the best predictor of what types of fungi are in your home is where your home is located." 
 
 Image copyright Science Photo Library Image caption Staphylococcus was among the 7,000 different types of bacteria found 
 
 The researchers also discovered an average of 7,000 different types of bacteria per household. 
 
 Some, such as Staphylococcus and Streptococcus, were commonly associated with human skin. 
 
 People do not need to worry about microbes in their home Dr Noah Fierer, University of Colorado at Boulder 
 
 However others, such as Bacteroides and Faecalibacterium, were linked to faeces. 
 
 But here, the species varied according to who - or what - was living in the house. 
 
 "We found distinct bacteria in homes that had women and homes that were male-only," said Dr Fierer. 
 
 "There are some kinds of bacteria that are more common on women's bodies than on men's, and we can see the impact of that on the bacteria found in house dust." 
 
 Pets also added to the microbe mix. 
 
 "Bringing a dog or cat into your home really has a significant effect on the bacteria you find in your home," explained Dr Fierer. 
 
 "It was surprising to us that it was such a strong influence - stronger than any other factor, stronger than where your home was located or the design of your home, for example." 
 
 While the study was carried out in the United States, Dr Fierer said that the findings would be relevant for other parts of the world. 
 
 Image copyright Anne Madden/Robin Hacker-Cary Image caption The researchers wanted to see how microbes varied across different households 
 
 The researchers now want to find out how sharing our homes with these organisms could affect human health. 
 
 While some microbes may be linked to disease and allergies, they say most are probably harmless - and some may even be beneficial. 
 
 Dr Fierer added: "People do not need to worry about microbes in their home. They are all around us, they are on our skin, they're all around our home - and most of these are completely harmless. 
 
 "It is just a fact of life that we are surrounded by these microbes." 
 
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– Last year, volunteers mailed in dust samples taken from above interior and exterior door frames in 1,200 homes across the US as part of a citizen science project called Wild Life of Our Homes. Now, scientists are reporting in the journal Proceedings of the Royal Society B that our dust reveals a lot about who we are and where we live. There are 9,000 unique species of microbes in our dust, reports the BBC, with an average of 7,000 of those being bacterial. There are also insect parts, pollen, dead animal cells, dry wall powder, carpet fibers, and soil particles. "I don't want any readers to be paranoid about this," Noah Fierer, a microbial ecologist at the University of Colorado at Boulder, tells the Los Angeles Times. "Most of the organisms are completely innocuous, and some may be beneficial." The No. 1 thing researchers can now predict about a home based on a simple analysis of dust? Whether cats or dogs live there. The type of fungi tends to be indicative of a home's geographical location, but bacteria change depending on who lives there—and that doesn't just mean what types of pets, but even whether a home is inhabited primarily by men or women. "There are some kinds of bacteria that are more common on women's bodies than on men's, and we can see the impact of that on the bacteria found in house dust," says Fierer. And while most of the fungi and bacteria are likely harmless, some could be linked to diseases and allergies, something scientists want to study further to discern how our dust specifically affects our health. (Did you know there's more dust in the world now than ever?)