Metadata is “data about data” – structured information describing, classifying or contextualising another set of data. In the web environment, this primarily means the information in an HTML document’s <head> that isn’t directly visible but gives search engines, browsers and social media platforms decisive hints about the content. Outside the web, metadata is everywhere: EXIF data in photos, ID3 tags in MP3s, header fields in PDF documents, frontmatter in Markdown files. The idea is always the same – structured supplementary information makes a data set understandable, searchable and automatically processable.
Types of metadata
| Category | What it’s used for | Examples |
|---|---|---|
| Descriptive metadata | Identifying and describing content | Title, author, keywords, description |
| Structural metadata | Mapping structure and relationships | Chapter structure in a PDF, sitemap hierarchy |
| Administrative metadata | Management and rights | Creation date, version number, creator, licence |
| Technical metadata | Format and device info | Resolution, codec, file size, EXIF capture data |
| Provenance metadata | Origin and change history | “Created with Adobe Photoshop”, editing versions |
Metadata on the web (HTML)
In the HTML <head>, several families of metadata are found, each with its own purpose and audience.
Basic meta tags
<title>Web Agency Stuttgart – Web Development & SEO | aceArt</title>
<meta name="description" content="Web agency from Stuttgart…">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta charset="utf-8">
<link rel="canonical" href="https://www.aceart.de/">
The <title> and the meta[name="description"] are the central content Google shows in the search results. More details in the entry on meta tags.
Open Graph (Facebook, LinkedIn, WhatsApp)
<meta property="og:title" content="Web Agency Stuttgart – aceArt">
<meta property="og:description" content="…">
<meta property="og:image" content="https://www.aceart.de/og-image.jpg">
<meta property="og:url" content="https://www.aceart.de/">
<meta property="og:type" content="website">
These Open Graph tags control how a link appears when shared on social media: title, description and preview image. Without them, the platform falls back on some image and the first scrap of text. The result usually looks unprofessional.
Twitter Cards
<meta name="twitter:card" content="summary_large_image">
<meta name="twitter:title" content="…">
<meta name="twitter:description" content="…">
<meta name="twitter:image" content="…">
Controls the preview on X (formerly Twitter), today largely falling back on Open Graph, but the Twitter tags override when needed.
Schema.org (JSON-LD)
<script type="application/ld+json">
{
"@context": "https://schema.org",
"@type": "Organization",
"name": "aceArt GmbH",
"url": "https://www.aceart.de/",
"telephone": "+49 711 21955380"
}
</script>
Schema.org markup as JSON-LD is the top tier of structured metadata. It enables rich results (rating stars, FAQ snippets, breadcrumbs, events, products) and gives search engines a semantic understanding of the content.
Robots control
<meta name="robots" content="index, follow">
<meta name="googlebot" content="max-snippet:200">
Controls how crawlers may index the page. Default: index, follow. Set noindex for sensitive areas like logins or filter URLs.
Metadata outside the web
- EXIF in JPEG/RAW: capture date, camera, lens, exposure, GPS coordinates. Careful: location data should often be removed before publishing photos (privacy)
- ID3 tags in MP3s: artist, album, title, cover image, BPM, genre
- PDF properties: author, title, keywords, creation date (readable via
pdfinfo, for example) - Office documents: editors, editing history, comments – can unintentionally reveal information about your own organisation
- YAML frontmatter in Markdown: title, date, description, tags – the foundation of static site generators like Hugo, Jekyll, Astro
Metadata and privacy
Metadata often contains more than its creators suspect. A few typical traps:
- EXIF GPS in photos: upload a holiday photo to social media and you might reveal your home address
- Office editors: the original author of a Word document remains visible, even after passing it to third parties
- PDF printer hints: “Created with Microsoft Print to PDF, user XYZ”
- Mail headers: sender IP, mail clients used, routing – relevant for privacy audits
Professional workflows therefore know the concept of metadata sanitisation before every publication. Tools like ExifTool, MAT2 or built-in Office functions (“Inspect Document”) help.
SEO and metadata – the most important levers
- A meaningful
<title>: 50–60 characters, keyword up front, USP clearly recognisable - A pointed
meta description: 150–160 characters, clear value + CTA, no pure keyword stuffing - Open Graph + Twitter Cards: for every piece of content – otherwise social shares look unprofessional
- Structured data (Schema.org): at least
Organization,BreadcrumbList, plusArticle,Product,FAQPagewhere fitting - Canonical and robots: set consistently; staging always on
noindex - hreflang for multilingualism: so the right language variant is served in the right region
Frequently asked questions about metadata
What’s the difference between metadata and data? Data is the actual content (text, image, audio). Metadata describes that content: when it was created, by whom, in which format, what it belongs to. The two often come together.
Is metadata the same as meta tags?
Meta tags are one specific form of metadata, namely those sitting in the HTML <head> as <meta> elements. Metadata is the broader umbrella term.
Why is metadata so important for SEO? Search engines can only understand content to the extent that it’s described in a structured way. Metadata supplies the decisive context: what is this about, who is the author, how does the page fit into the site hierarchy. Without metadata, Google has to guess.
How do I remove metadata from images and PDFs?
- Images: ExifTool (
exiftool -all= file.jpg) or online services like metadata2go.com - PDFs: qpdf, exiftool, or Adobe Acrobat → “Examine Document”
- Office: the built-in “Inspect Document” function (File → Info)
Can metadata be manipulated? Yes, all metadata is editable. Authentic metadata can only be recognised via cryptographic signatures (e.g. C2PA / content provenance), a growing topic in the context of AI-generated content.
Conclusion
Metadata is the invisible layer that makes the web searchable, shareable and automatable. Anyone who thinks it through from the start of a web project (title, description, Open Graph, Schema.org, robots) lays the foundation for good visibility, professional social shares and clean rich results. We set up the complete metadata architecture in every web project and audit it as part of our SEO consulting. Feel free to reach out for a no-obligation consultation.