WordPress is open-source software, one of the most popular CMS (Content Management System) and website building platforms. You ask, what is WordPress? I’d suggest A beginner’s guide to WordPress.
Before we get to WordPress themes and plugins, let’s understand what a web page is, and all its different components. A website majorly has two components, namely: Design and Functionality. Well, there’s more as your website’s design, features, and little trickeries are made visible by some very important things. These things are HTML, CSS, JS (JavaScript).
HTML (Hyper Text Markup Language)
HTML (Hyper Text Markup Language) is the set of markup codes and syntax that are inserted into a file, which is displayed on a webpage. Simply speaking, HTML directs the web browser on how to display a page, header, footer, pictures, fonts, etc. This is what HTML looks like.
CSS (Cascading Style Sheets)
CSS (Cascading Style Sheets) is the language that tells the browser how to present the website. It handles the presentation of your website, what goes where, in what color, in what font, etc. Below is the example of how a website looks with CSS. (The above and below images are of the same website! 
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JS (JavaScript)
JS (JavaScript) adds dynamic and interactive elements to a website. More than 90% of the websites use JS, for a more intuitive, optimized, and faster experience. For example, a real-time update on the website, changes in product cart, live match scores, etc. are achieved with JS.
Coming back to themes and plugins..
The design part of your website mainly comprises templates. Templates are the layout and design elements of your website. They are like the skin of your website. It is a framework that houses all the fonts, colors, designs, etc. in it.
Functionality is something that offers additional features that you might or might not need. For example, the contact form (you may know it as newsletter or subscribe form), payment gateways, etc.
Now, let’s ignite the chambers, and fire up some engines, To Planet WordPress! 
WordPress has two pillars, which hold the fort together, and give you the design and flexibility that we all love so much.
The two pillars making WordPress websites magical and breathtaking are – Themes and Plugins. People embrace, for we are going to understand what WordPress themes and plugins are? And what is the difference between themes and plugins? (It’s pretty simple actually, I was just creating some hype). 
WordPress themes give a framework or a structure, how the website is going to look, what goes where, and other design elements (think of it as a body structure and clothes on a person). WordPress plugins are little plugs that look small but pack the force of an atom bomb 
(think of plugins as attributes/features of a person. It could be a few and it could be many).
Continue reading:https://wpwhiteboard.com/all-about-wordpress-themes-plugins/
