What's WikiData and Usage?

WikiData is an open source platform to find different types of data. It's a collaboratively modified source, and keeping structured data. It's a free source, so you can use its data without any permission. It's a multilingual platform, you can browse, edit in different languages. It also support other sister platforms like Wikipedia, Wikimedia.

It has tools for users to collect data from Wikidata. It has "Query Service" for users to run different queries to observe data at Wikidata.

An example Query: Countries that have sitelinks to en.wiki

SELECT ?country ?countryLabel ?article WHERE {

   ?country wdt:P31 wd:Q3624078 . # sovereign state
   ?article schema:about ?country .
   ?article schema:isPartOf <https://en.wikipedia.org/>.

   SERVICE wikibase:label {
       bd:serviceParam wikibase:language "en"
   }
}