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• A single-page application (SPA) is a web application or website that interacts with the user by dynamically rewriting the current web page with new data from the web server, instead of the default method of browser loading entire new pages.

  The goal is faster transitions that make the website fell more like a native app.

• The is a permissive free software license written by the Apache Software Foundation(ASF).

  It allows users to use the software for any purpose, to distribute it , to modify it, and to distribute modified versions of the software under the terms of the license, without concern for royalties.

• A petabytes is $10^{15}$ bytes of digital information.

  The unit symbol for the petabyte is PB.