The Centers for Disease Control and Prevention describes social distancing as "remaining out of congregate settings, avoiding mass gatherings and maintaining distance (approximately 6 feet or 2 meters) from others when possible."
Why? When someone coughs or sneezes, small drops of liquid spray from their nose or mouth. If you're standing too close, you can breathe in the droplets, which may contain the coronavirus if the person coughing is infected, according to the World Health Organization.
为什么？ 当某人咳嗽或打喷嚏时，会从他们的鼻子或嘴里喷出一小滴飞沫。 根据世界卫生组织的说法，如果您站得太近，则可以吸入飞沫，如果咳嗽的人已经被感染，飞沫中则可能含有冠状病毒。
The "6 feet of distance" rule comes from studies of respiratory physiology, said Dr. William Schaffner, infectious disease expert at Vanderbilt University.
范德比尔特大学（Vanderbilt University）传染病专家威廉·沙夫纳（William Schaffner）博士说，“ 6英尺远”的要求来自对呼吸生理学的研究。
"Without a cough or a sneeze, if we exhale, the distance 3 to 6 feet from each other is called the breathing zone. And it's in that kind of volume of air that what I exhale begins to mix with the air that's already in the room," Schaffner said. "So if you're standing within 3 to 6 feet of me, you may well inhale some of what I exhale. And of course if I have the virus, what I'm exhaling microscopically contains the virus."
If you're finding it hard to estimate what exactly 6 feet looks like, we've got a list of animals, people and things you can keep in mind to help you judge the appropriate distance you should keep from other people.
Two Golden Retrievers standing nose to tail
The average Golden Retriever has a body length of 37 to 42 inches. Two of these dogs should amount to just over 72 inches, or 6 feet.
A man wearing a top hat
A man of average height stands at 5 feet 9 inches tall -- if that man wears a President Abraham Lincoln-esque top hat, he'd be just over the distance we're advised to keep from others.
An average sedan
Think of the width of your car when trying to gauge an appropriate distance -- an average large sedan is a little more than 6 feet wide.
A standard three-seat sofa can be up to 6 feet long -- which means that you and the person sitting on the other end of it probably aren't far away enough from each other.
The length of a mattress
The lengths of full- and twin-size beds are about 6.2 feet from top to bottom.
Two adult cats
Cat lovers may find it easy to commit this comparison to memory: Two male adult cats, at 35 inches each from their heads to the tips of their tails, can amount to nearly 72 inches.
A door should be relatively easy to find when questioning whether you and your friend should move farther apart. Six feet is a little shorter than the average modern door, which runs from 78 to 80 inches.