\nAttribute Values\n\nHTML5 attribute values can be unquoted.\n\nWe recommend using quotes for attribute values:\n\nIf the attribute value contains spaces, quotes are required.\nMixed styles are not recommended; a consistent style is suggested.\nAttribute values with quotes are easier to read.\n\nThe following example attribute value contains spaces and does not use quotes, so it will not work:\n\n\n\nThe following uses double quotes and is correct:\n\n\nImage Attributes\n\nImages usually use the alt attribute. When the image cannot be displayed, it can replace the image display.\n\n\n\nDefining the size of the image in advance can reserve specified space during loading and reduce flickering.\n\n\nSpaces and Equal Signs\n\nSpaces can be used before and after the equal sign.\n\nBut we recommend using fewer spaces:\n\nAvoid Long Lines of Code\n\nUsing an HTML editor, scrolling left and right through code is inconvenient.\n\nTry to keep each line of code less than 80 characters.\n\nBlank Lines and Indentation\n\nDo not add blank lines for no reason.\n\nAdd a blank line for each logical block of code to make it easier to read.\n\nUse two spaces for indentation; using TAB is not recommended.\n\nDo not use unnecessary blank lines and indentation between shorter code segments.\n\nUnnecessary blank lines and indentation:\n\n

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HTML

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\n ，What is learned is not only technology, but also dreams.。\n ，What is learned is not only technology, but also dreams.。\n ，What is learned is not only technology, but also dreams.,\n ，What is learned is not only technology, but also dreams.。\n

\n\nRecommended:\n\n

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，What is learned is not only technology, but also dreams.。\n，What is learned is not only technology, but also dreams.。\n，What is learned is not only technology, but also dreams.。\n，What is learned is not only technology, but also dreams.。

\n\nTable Example:\n\n \n \n \n \n \n \n \n \n \n \n \n \n

Name	Description
A	Description of A
B	Description of B

\nList Example:\n

\n
1. London
\n
2. Paris
\n
3. Tokyo
\n

\nOmit and ?\n\nIn standard HTML5, the and tags can be omitted.\n\nThe following HTML5 document is correct:\n\nExample:\n\n \n\n

This is a title.

\n

This is a paragraph.

\n\nTry it »\n\nOmitting the and tags is not recommended.\n\nThe element is the root element of the document, used to describe the language of the page:\n\nDeclaring the language is for the convenience of screen readers and search engines.\n\nOmitting or will crash in DOM and XML software.\n\nOmitting will cause errors in older browsers (IE9).\n\nOmit ?\n\nIn standard HTML5, the tag can be omitted.\n\nBy default, the browser will add the content before to a default element.\n\nExample\n\n\n\n

This is a title.

\n

This is a paragraph.

\n\nTry it »\n\tOmitting the head tag is not recommended at present.\nMetadata\n\nIn HTML5, the \n\nThe title and language can help search engines quickly understand the topic of your page:\n\n \n \n\nHTML Comments\n\nComments can be written between :\n\n\n\nLonger comments can be written across multiple lines between :\n\n\n\nIndent the first character of a long comment by two spaces to make it easier to read.\n\nStylesheets\n\nStylesheets use a concise syntax format (the type attribute is not required):\n\nShort rules can be written on one line:\n\np.into {font-family: Verdana; font-size: 16em;}\n\nLong rules can be written across multiple lines:\n\nbody {\n background-color: lightgrey;\n font-family: "Arial Black", Helvetica, sans-serif;\n font-size: 16em;\n color: black;\n}\nPlace the left curly brace on the same line as the selector.\nAdd a space between the left curly brace and the selector.\nUse two spaces for indentation.\nAdd a space between the colon and the property value.\nUse a space after commas and symbols.\nUse a semicolon at the end of each property and value.\nOnly use quotes when the property value contains spaces.\nPlace the right curly brace on a new line.\nMaximum of 80 characters per line.\n\tAdding spaces after