Dublin Core is a metadata standard, even though the use of Dublin Core meta-tags could increase the pages prominence in search engine retrieval lists.
\par It provides a simple and standardised set of conventions for describing things online in ways that make them easier to find. Dublin Core is widely used to describe digital materials such as video, sound, image, text, and composite media like web pages. Implementations of Dublin Core typically make use of XML and are Resource Description Framework based. Dublin Core is defined by ISO in 2003 ISO Standard 15836, and NISO Standard Z39.85-2007. The "Core" refers to the fact that the metadata element set is a basic but expandable "core" list. The Dublin Core Metadata Initiative (DCMI) is an organization providing an open forum for the development of interoperable online metadata standards that support a broad range of purposes and business models.\\The Dublin Core standard includes two levels: Simple and Qualified. Simple Dublin Core comprises fifteen elements; Qualified Dublin Core includes three additional elements (Audience, Provenance and RightsHolder), as well as a group of element refinements (also called qualifiers) that refine the semantics of the elements in ways that may be useful in resource discovery.\\The Simple Dublin Core Metadata Element Set (DCMES) consists of 15 metadata elements:

   1. Title
   2. Creator
   3. Subject
   4. Description
   5. Publisher
   6. Contributor
   7. Date
   8. Type
   9. Format
  10. Identifier
  11. Source
  12. Language
  13. Relation
  14. Coverage
  15. Rights

Each Dublin Core element is optional and may be repeated. The DCMI has established standard ways to refine elements and encourage the use of encoding and vocabulary schemes. There is no prescribed order in Dublin Core for presenting or using the elements.
\item Delicious (formerly del.icio.us, pronounced "delicious") is a social bookmarking web service for storing, sharing, and discovering web bookmarks. The site was founded by Joshua Schachter in 2003 and acquired by Yahoo! in 2005. It has more than five million users and 150 million bookmarked URLs.It is headquartered in Santa Clara, California.\par Delicious uses a non-hierarchical classification system in which users can tag each of their bookmarks with freely chosen index terms (generating a kind of folksonomy). A combined view of everyone's bookmarks with a given tag is available; for instance, the URL "http://delicious.com/tag/wiki" displays all of the most recent links tagged "wiki". Its collective nature makes it possible to view bookmarks added by similar-minded users.