Underside view of the Spider repairing its web. Note the new line spooling from her spinnerets at the lower mid-part of its body. (Thanks Christine for I.Ding the "spinnerets" for me.)

Did you know that there are over 10,000 species of Orb-weavers that make up about 25% of spider diversity. That they have eight similar eyes and hairy or spiny legs. (from Wikipedia)

Generally, orb-weaving spiders are three-clawed builders of flat webs with sticky spiral capture silk. The building of a web is an engineering feat, begun when the spider floats a line on the wind to another surface. The spider then secures the line and then drops another line from the center, making a "Y". The rest of the scaffolding follows with many radii of non-sticky silk being constructed before a final spiral of sticky capture silk. (Wikipedia)