Thanks to HTML and the internet, we are accustomed to navigating from page to page through links. The concept of linked data is to extend this principle from pages to a much more detailed level: linking concepts, their relationships, and specific values in a semantic standard. You might have heard the phrase "semantic web" before. Linked data is the key to making these connections happen.
Similar to other kinds of databases, linked data is searchable or queryable. Since linked data can describe things and their relationships, people can use tools to answer questions about these things and relationships.