Description: Tell the search engine the Keywords of your web page (Keywords)
Robots are used to tell search Robots whether a page needs an index or not. The Content parameters are all, None, index, noindex, follow, and nofollow. The default is all.
Viewport (Windows/mobile terminal) Description: ViewPort is the visual area of the user’s web page.
Http-equiv = “X-UA-compatible” (this is a definition of document compatibility mode)
force browsers to use the WebKit kernel.