HTML (Hyper Text Markup Language)  to define the content of web pages

CSS to specify the layout of web pages

JavaScript to program the behavior of web pages

PHP

HTML Cheat Sheet or Print HTML Cheat Sheet
What is HTML?
"Simple HTML Document "What Is HTML Element? Nested HTML Element Empty Element "Page Structure" "HTML Display"
HTML Basic
Body br Comment Doctype Declaration Headings h1-to-h6 Head
hr HTML Images Links Paragraph Source Title

HTML - Block - Inline - Elements

Block Level Elements

Block Element always starts on a new line
Always takes up the full width available (stretches out to the left and right as far as possible).

<address> <article> <aside> <blockquote> <canvas> <dd> <div>
<dl> <dt> <fieldset> <figcaption> <figure> <form> <footer>
<header> <hr> <li> <main> <noscript> <ol> <p>
<pre> <h1-h6> <section> <table> <tfoot> <ul> <video>

Inline Elements

An inline element does not start on a new line.
An inline element only takes up as much width as necessary
The <span> tag is an inline container used to mark up a part of a text, or a part of a document.
The <span> tag is easily styled by CSS or manipulated with JavaScript using the class or id attribute.
The <span> tag is much like the <div> element, but <div> is a block-level element and <span> is an inline element.

<a> <abbr> <b> <bdo> <br> <button> <cite>
<code> <dd> <dt> <dfn> <em> <i> <img>
<input> <kbd> <label> <map> <object> <output> <small>
<span> <strong> <sup> <sub> <samp> <script> <select>
<textarea> <time> <tt> <var>

This sidenav is always shown.