Chemical element element (by mass) making up Earth, while oxygen is the most common element in the Earth's crust. Chemical elements constitute all of the ordinary matter of the universe. However astronomical observations suggest that ordinary observable matter makes up only about 15% of the matter in the universe: the remainder is dark matter; the composition of this is unknown, but it is not composed of chemical elements. The two lightest elements, hydrogen and helium, were mostly formed in the Big Bang and are the most common elements in the universe. The next three elements (lithium, beryllium and boron) were formed mostly
Canonical link element document. 11. Site Host https://sitehostnp.com/canonicalization/canonical-link-element/. What s "rel=canonical" link element and how it should be used for search engines. Published on 14 June 2018. Canonical link element A canonical link element is an HTML element that helps webmasters prevent duplicate content issues in search engine optimization by specifying the "canonical" or "preferred" version of a web page. It is described in RFC 6596, which went live in April 2012. A major problem for search engines is to determine the original source for documents that are available on multiple URLs. Content duplication can happen in a many ways, including: Duplicate content