Everyone who has heard of HTML5 knows its power, such as more descriptive markup, multimedia support that is less dependent on plug-ins, cross-document message communication, Web Sockets, client-side storage, more powerful forms, and improved accessibility. flexibility, advanced selectors, and powerful visual effects. Without further ado, let’s go into details
Abandoned tags and attributes
Abandoned tags
Abandoned because they can be replaced with CSS
basefont
big
center
font
strike
tt
u
s
Deprecated due to breaking usability and accessibility
frame
frameset
noframes
Causing confusion, infrequent
acronym is used and abandoned because it often clutters the page. You can use abbr instead.
applet is abandoned because you can use object instead.
isindex is abandoned. Because using form controls instead of
dir is deprecated because using ul instead of
noscript elements can only be used in HTML, not XML.
Obsolete attributes
align
link, vlink, alink and text attributes on the body tag
bgcolor
height and width
scrolling attributes on iframe elements
valign
hspace and vspace
cellpadding, cellspacing and border attributes on table tags
The visual effects achieved by the above elements can be achieved with css, so they are abandoned
In addition, the target attribute is abandoned in the specification
The profile attribute on the head tag will no longer be supported
The longdesc attribute of img and iframe elements has also been removed
There are alternatives to these attributes in the HTML5 specification, you can view HTML Standard
New structural tags and attributes
Document type declaration
<!doctype html><html> <head> <meta charset="UTF-8"> <title>文章标题</title> </head> <body>
Article text part

The roles of HTML, CSS and JavaScript in web development are: 1. HTML is used to build web page structure; 2. CSS is used to beautify the appearance of web pages; 3. JavaScript is used to achieve dynamic interaction. Through tags, styles and scripts, these three together build the core functions of modern web pages.

Setting the lang attributes of a tag is a key step in optimizing web accessibility and SEO. 1) Set the lang attribute in the tag, such as. 2) In multilingual content, set lang attributes for different language parts, such as. 3) Use language codes that comply with ISO639-1 standards, such as "en", "fr", "zh", etc. Correctly setting the lang attribute can improve the accessibility of web pages and search engine rankings.

HTMLattributesareessentialforenhancingwebelements'functionalityandappearance.Theyaddinformationtodefinebehavior,appearance,andinteraction,makingwebsitesinteractive,responsive,andvisuallyappealing.Attributeslikesrc,href,class,type,anddisabledtransform

TocreatealistinHTML,useforunorderedlistsandfororderedlists:1)Forunorderedlists,wrapitemsinanduseforeachitem,renderingasabulletedlist.2)Fororderedlists,useandfornumberedlists,customizablewiththetypeattributefordifferentnumberingstyles.

HTML is used to build websites with clear structure. 1) Use tags such as, and define the website structure. 2) Examples show the structure of blogs and e-commerce websites. 3) Avoid common mistakes such as incorrect label nesting. 4) Optimize performance by reducing HTTP requests and using semantic tags.

ToinsertanimageintoanHTMLpage,usethetagwithsrcandaltattributes.1)UsealttextforaccessibilityandSEO.2)Implementsrcsetforresponsiveimages.3)Applylazyloadingwithloading="lazy"tooptimizeperformance.4)OptimizeimagesusingtoolslikeImageOptimtoreduc

The core purpose of HTML is to enable the browser to understand and display web content. 1. HTML defines the web page structure and content through tags, such as, to, etc. 2. HTML5 enhances multimedia support and introduces and tags. 3.HTML provides form elements to support user interaction. 4. Optimizing HTML code can improve web page performance, such as reducing HTTP requests and compressing HTML.

HTMLtagsareessentialforwebdevelopmentastheystructureandenhancewebpages.1)Theydefinelayout,semantics,andinteractivity.2)SemantictagsimproveaccessibilityandSEO.3)Properuseoftagscanoptimizeperformanceandensurecross-browsercompatibility.


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