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Metadata说明.md

File metadata and controls

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---

title: Metadata说明

date: 2020-01-16

categories:
   - Metadata

tags:
   - Metadata


description: 
​
---

from:https://dataedo.com/kb/data-glossary/what-is-metadata

描述数据的数据，或者是数据的属性

Metadata is simply data about data. It means it is a description and context of the data. It helps to organize, find and understand data. Here are a few real world examples of metadata:

Typical metadata

Those are some typical metadata elements:

  1. Title and description,
  2. Tags and categories,
  3. Who created and when,
  4. Who last modified and when,
  5. Who can access or update.

A photo

Every time you take a photo with today's cameras a bunch of metadata is gathered and saved with it:

  • date and time,
  • filename,
  • camera settings,
  • geolocation.

A book

Each book has a number of standard metadata on the covers and inside. This includes:

  • a title,
  • author name,
  • publisher and copyright details,
  • description on a back,
  • table of contents,
  • index,
  • page numbers.

A blog post

Every blog post has standard metadata fields that are usually at before first paragraph. This includes:

  • title,
  • author,
  • published time,
  • category,
  • tags.

Email

img

Every email you send or receive has a number of metadata fields, many of which are hidden in the message header and not visible to you in your mail client. This metadata includes:

  • subject,
  • from,
  • to,
  • date and time sent,
  • sending and receiving server names and IPs,
  • format (plain text of HTLM),
  • anti-spam software details.

Word document

Every word processing software collects some standard metadata and enables you to add your own fields for each document. Typical fields are:

  • title,
  • subject,
  • author,
  • company,
  • status,
  • creation date and time,
  • last modification date and time,
  • number of pages.

A spreadsheet

img

Spreadsheets contain a few metadata fields:

  • tab names,
  • table names,
  • column names,
  • user comments.

Relational database

Relational databases (most common type of database) store and provide access not only data but also metadata in a structure called data dictionary or system catalog. It holds information about:

  • tables,
  • columns,
  • data types,
  • constraints
  • table relationships,
  • and many more

Browse sample database metadata

Learn more about metadata in relational databases

Discover and share database metadata

Extract metadata from databases, document schema and share in convenient HTML.

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Computer files

All the fields you see by each file in file explorer is actually metadata. The actual data is inside those files. Metadata includes:

  • file name,
  • type,
  • size,
  • creation date and time,
  • last modification date and time.

Web page

Every web page has a number of metadata fields:

  • page title,
  • page description,
  • icon.

Paper files

Paper document files have often administrative metadata that help manage documents. This might include:

  • letter for files organized alphabetically,
  • access control information ("classified" for instance),
  • logos.

Summary

Those were my examples. I hope by now you have pretty good understanding of what metadata is.