WordPress is a very popular open source CMS (Content Management System) that is widely used for website building. Here are the reasons why WordPress is recommended for website building:

1. Easy to use and manage: WordPress provides an intuitive user interface that makes it easy for even beginners to create and manage websites. Whether you have a personal blog, a small business website or a large portal, you can use WordPress to build your website.
2. Tons of Themes and Plugins: WordPress has a rich library of themes and plugins, resources that can help you quickly build a beautiful, fully functional website. You can choose from thousands of themes to change the look and feel of your site, or use plugins to add more functionality such as social media sharing, SEO optimization, security, and more.
3. Highly Customizable: WordPress is highly customizable to meet the needs of a variety of websites. If you have some technical knowledge, you can also achieve a higher level of customization by editing the theme files and plugin code.
4. Excellent SEO Features: WordPress offers powerful SEO plugins such as Yoast SEO and All-in-One SEO Pack to help you optimize your website's content, titles, keywords, and meta descriptions to improve your website's ranking in search engines.
5. Community Support: WordPress has a large community, which means you can always get support and help. Whether you're looking for a solution or inspiration, the WordPress community can help.

In summary, WordPress is a powerful, easy-to-use, highly customizable and widely supported CMS for building all types of websites.