Automatic watches are considered the highest caliber of watch. They wind themselves automatically, using power from the movements of your wrist, and the second hand moves in smooth movements, rather than ticking. If a watch is automatic, it should be listed on the product description page. If you take off your automatic watch, it will eventually stop working after a few days. You'll need to rewind it before it starts again. Quartz watches are powered by a small crystal, a battery, and a few small motors. Though they're now considered less high-end than automatic watches, quartz watches are still perfectly serviceable, and they actually keep time more accurately than automatic watches. They tend to be slightly cheaper as well. The second hand in a quartz watch will move forward in short jerks, making a ticking noise. You'll need to replace the batteries in your quartz watch every few years. Check the product description to see if a watch is quartz. Watches are made for all different types of lifestyles and needs, with several "genres" to choose from. One of the positives of shopping online is that you'll get to look at and consider all of the different genres before committing to one! The main styles you'll want to consider are: Diving watches, which are 100% waterproof, are designed to work under heavy water pressure, and have luminous dials and hands. Dress watches, which are used more for adornment than for function. These watches will be understated, with a simple face and strap, and are often made from precious metals. Aviation watches, made for pilots, which often convey large amounts of information in addition to the time, such as altitude. Some aviation watches also include a second hour hand so pilots can tell the time in 2 time zones at once. Driving watches, which typically include features like a stopwatch and "tachymeter" for measuring speed. Keeping the face of your watch scratch-free can make it look clean and new even after years of wear. Look for sapphire crystal for the strongest scratch-proofing power, or choose mineral crystal for a scratch-resistant watch. Acrylic crystal is cheaper, but prone to light scratching. Look for this information in the watch's product specifications tab, under "dial window material type." The strap, or bracelet, of your watch will have a big impact on its overall look. A metal bracelet is held together by links, giving it a shiny gleam that looks great with heavier-looking watches. A leather watch strap looks great on formal, dressy watches. It's understated and quietly classy, making it a timeless, classic choice when you're dressing up. When buying online, you won't be able to feel the leather first, so look at the watch's description and any reviews to get an idea of how it'll feel on your wrist. You won't be able to try on your watch before buying it, so it's important to know exactly what case diameter and strap size you'll need. All sizing information should be available on the watch's page, and the retailer may also offer a strap sizing chart, as sizes can vary between brands. Sizing information is measured in millimeters. If your wrists are smaller, a 34-40 mm case diameter will be fine. If you have larger wrists, try a diameter closer to 46 mm. A regular strap length (neither "extra-long" nor "extra-short") should work for most people. You can also use a tape measure to determine the width of your wrist and buy a strap that's several millimeters longer, or consult the brand's sizing chart. If you buy casual or formal watches, you can size your watch by adding or removing links.
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One-sentence summary -- Choose an automatic watch for ease and style. Go with a quartz watch for greater accuracy at a lower price. Pick a watch style, like sport or dress, that fits your needs. Choose a durable, scratch-resistant watch if you plan to wear it on a daily basis. Go with a metal bracelet for a brighter, chunkier look. Choose a leather strap for a dressier style. Size your wrist and choose a case and bracelet that will fit.

Article: Vitamin D is an important nutrient for the body. Vitamin D is involved in the proper functioning of the immune system, cell growth, and cell regulation. It also aids the body in numerous ways, such as encouraging calcium absorption, promoting bone growth, and aiding in bone remodeling. Vitamin D prevents rickets, osteomalacia (softening of the bone), and osteoporosis (brittle bones). It has also been associated with cardiovascular disease, cognitive impairment in older people, asthma in children, and even cancer. Low levels of Vitamin D also contribute to the risk of colon and pancreatic cancer. Vitamin D deficiencies can increase the risk of high blood pressure, multiple sclerosis, autoimmune diseases, insulin resistance, and Type 1 and Type 2 diabetes. Some people are more at risk than others for vitamin D deficiency. If you are in one of the at risk categories, make sure to eat as much vitamin D as possible. However, even if you don't fall under the typical category of someone who might be deficient, you could still be at risk. Have your blood tested to find out whether or not you are deficient, especially if you fall into one of the following groups: Elderly adults Infants who are breastfed Those with darker skin Individuals who do not get enough sun exposure Individuals who are obese, overweight, and those who have had gastric bypass surgery People with fat malabsorption conditions Those allergic to milk Anyone who eats a vegan diet For people ages one through 70, they need 600 IU (15 mcg) of vitamin D a day. Under one year only needs 400 IU (10 mcg), and over 70 needs 800 IU (20 mcg). Vitamin D can be taken as a supplement, as either D2 or D3. You can also get vitamin D from the sun. Spend 10 to 20 minutes in the afternoon sun two to three times a week without sunscreen. Make sure you expose you face, arms, and legs to the sun. Using a tanning bed is not the same as spending time in the sun. Make sure to consult a physician before taking any supplements, especially if you are on other medications.
Question: What is a summary of what this article is about?
Know why vitamin D is important. Learn who is at risk for deficiency. Know how much vitamin D you need. Understand where else to get vitamin D.