1. Web standard composition: structure, representation, behavior
1.1 Structure (HTML): It is used to organize and classify the structure of web pages.
1.2 Representation (CSS): Used to set the style, color, size, appearance, etc. of web page elements.
1.3 Behavior (JS): Web page model definition and interactive writing.
2. Tags: title tags, text format tags, paragraph tags, image tags
2.1标题标签：<h1></h1>、<h2></h2>、<h3></h3>、<h4></h4>、 <h5></h5>、<h6></h6>
The h1 tag can only be used once in a page;
The title tag is automatically bolded and wraps;
Blank lines are generated up and down;
The font size of the title is h1, the largest and so on
2.2 Text format label
Bold: <strong>Bold</strong> & <b>Bold</b> <br/>
Tilt: <em>Tilt</em> &<i>Tilt</i> <br/>
Strikethrough: <del>Strikethrough</del> & <s>Strikethrough</s> <br/>
Underline: <ins>underline</ins>& underline
2.3 Paragraph tags
<p></p>
Paragraph tags, the text will be displayed in a new line according to the size of the browser.
Keep gaps between paragraphs.
<br/> Single label, line break label, forced line break of text (line break only, no segmentation)
2.4 Image tags
<img src="" alt="" title="" height="" width="" border="" />
Attribute + attribute value + description
src: Image path, this is a required attribute.
alt: text, replacement text. If the picture is not displayed, the prompt text information in the alt attribute is displayed. This can be left blank.
title: text, prompt text. When the mouse hovers over the picture, the text information in the title attribute is displayed.
height: pixels, set the height of the picture. Only fill in one with width attribute to achieve year-on-year scaling.
width: pixels, set the width of the picture. Only fill in one with the height attribute to achieve year-on-year scaling.
border: pixels, set the border thickness of the picture. It is generally controlled in CSS.
3、<div></div>&<span></span>
3.1 <div></div>, div is the abbreviation of division. The label has no semantics and is similar to a box. This label is on its own line. Only one <div> per line (big box)
3.2<span></span> Span, span. The text in the span tag can be displayed side by side. There can be multiple <span>s in a row (small box)