Firewalld is one of the Linux firewall management tool and it is available on the in the Ubuntu's default repositories, therefore it is available to
be installed from these repositories using the apt packaging system.
Keywords are special words in the programing language which have reserved use in the language.
Keywords may not be used as identifiers in Java; for example you cannot declare a field whose name is a keyword.
The sitemap's a file place on your website that will enable Google and other search engines to crawl better and
understand the structure of the site. Sitemaps also tell search engines which pages on your site are most
important. It's a binder of your website's content.