Шпора по HTML

What HTML code is obligatory for a proper html-document?

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Page title</title>
</head>
<body>

</body>
</html>

Web forms how-tos:

How to turn autocomplete on?

Special input types:

Data type	HTML code
email	<input type="email" inputmode="email" autocapitalize="off" autocorrect="off" autocomplete="email">
phone number	<input type="tel" inputmode="tel" autocorrect="off" autocomplete="tel">
credit card # with spaces allowed	<input type="text" novalidate autocorrect="off" autocomplete="cc-number">
credit card # without spaces	<input type="number" inputmode="numberic" pattern="[0-9]*" novalidate autocorrect="off" autocomplete="cc-number">
credit card security code	<input type="text" inputmode="decimal" pattern="[0-9]*" novalidate autocorrect="off" autocomplete="cc-csc">
any country ZIP code	<input type="text" pattern="[0-9A-Za-z]*" novalidate autocorrect="off" >
date with date picker	<input type="date">

Web-media file formats:

images: jpg, (png, gif) => webp
video: for video file playback - MP4 (w/ h.265 codec); for playing a video stream - WebM and OGG
audio: mp3, aac, ogg, mp4a

File formats wiki:

Video content is encoded using codec standard (MPEG-4, h.264/AVC, h.265/HEVC, VP9 (not supported by Apple devices), AV1) and stored using container format (MP4, AVI, WMV, MOV, FLV, MKV, AVC, AVCHD, WEBM)

Container:	Codec:	Compression rate	Video quality	File size	Compatibility	Total score for web
MP4	MPEG-4 (DivX/XviD + MP3)	4+	4+	4+	4+	4+
	MPEG-4 (h.264 (AVC) + MP3)	4+	4+	4+	5	5
	MPEG-4 (h.265 (HEVC) + MP3)	5	5	5	5	5
	AV1
	MPEG-2	2	4	2	2	0
	VP9
MOV	MPEG-4	4	5	4	2	2
AVI		3	5	3	4	3
WMV		5	4	5	3 (no iPhones)	3
FLV		5	4	5	3 (no iPhones)	3
WEBM					4	4
MKV