What is the difference between a URI, a URL and a URN?

From RFC 3986:

A URI can be further classified as a locator, a name, or both. The term “Uniform Resource Locator” (URL) refers to the subset of URIs that, in addition to identifying a resource, provide a means of locating the resource by describing its primary access mechanism (e.g., its network “location”). The term “Uniform Resource Name” (URN) has been used historically to refer to both URIs under the “urn” scheme [RFC2141], which are required to remain globally unique and persistent even when the resource ceases to exist or becomes unavailable, and to any other URI with the properties of a name.

So all URLs are URIs, and all URNs are URIs – but URNs and URLs are different, so you can’t say that all URIs are URLs.

If you haven’t already read Roger Pate’s answer, I’d advise doing so as well.

Related Posts:

  1. How are parameters sent in an HTTP POST request?
  2. What’s the point in having “www” in a URL?
  3. Should a 502 HTTP status code be used if a proxy receives no response at all?
  4. HTTP Status 504
  5. What is the difference between POST and GET? [duplicate]
  6. Do I need Content-Type: application/octet-stream for file download?
  7. Problem HTTP error 403 in Python 3 Web Scraping
  8. application/x-www-form-urlencoded or multipart/form-data?
  9. Problem HTTP error 403 in Python 3 Web Scraping
  10. application/x-www-form-urlencoded or multipart/form-data?
  11. Is 418 “I’m a teapot” really an HTTP response code?
  12. How to define the basic HTTP authentication using cURL correctly?
  13. How to define the basic HTTP authentication using cURL correctly?
  14. “Cannot GET /” with Connect on Node.js
  15. “CAUTION: provisional headers are shown” in Chrome debugger
  16. What’s the difference between a POST and a PUT HTTP REQUEST?
  17. How do I send a POST request with PHP?
  18. Custom Tumblr theme wont save because of non-https urls?
  19. Why is it said that “HTTP is a stateless protocol”?
  20. What’s the difference between using application/csv vs text/csv? [duplicate]
  21. What’s different between URI, request-URI and URL?
  22. What are all the possible values for HTTP “Content-Type” header?
  23. Can a URL contain a semicolon and still be valid?
  24. What is the difference between PUT, POST and PATCH?
  25. Can we use & in url?
  26. What’s the difference between “Request Payload” vs “Form Data” as seen in Chrome dev tools Network tab
  27. Exception in thread “main” java.net.NoRouteToHostException: No route to host
  28. ndroid 8: Cleartext HTTP traffic not permitted
  29. Can PHP cURL retrieve response headers AND body in a single request?
  30. Setting Curl’s Timeout in PHP
  31. Why am I suddenly getting a “Blocked loading mixed active content” issue in Firefox?
  32. wget: unable to resolve host address `http’
  33. Are HTTP headers case-sensitive?
  34. When looking at the differences between X-Auth-Token vs Authorization headers, which is preferred?
  35. WordPress HTTP parameter pollution
  36. Does WordPress send data about your blog to WordPress.org or Automattic?
  37. Hiding WordPress REST API v2 endpoints from public viewing
  38. Does WordPress only support HTTP 1.1?
  39. How do I troubleshoot responses with WP HTTP API?
  40. Is curl required?
  41. The resource was preloaded using link preload but not used within a few seconds
  42. using wp_remote_get to retrieve own url on local host
  43. Using wp-cron in backpress – problems with wp_remote_post, fsockopen error
  44. Running index.php from command line & load balancer health checks
  45. Enable CORS in wordpress
  46. Change port of wordpress
  47. How to get value of custom http header?
  48. Several times request to load plugins when sending one request
  49. why is $_REQUESt[‘redirect_to’] empty?
  50. Get “HTTP/1.1 406 Not Acceptable” when accesing my website with Delphi Indy Control
  51. WordPress HTTP 500 Error “page isn’t working”
  52. For what is the “.well-known”-folder?
  53. Human readable format for http headers with tcpdump
  54. How to make wireshark filter POST-requests only?
  55. Image file urls still point to http instead of https
  56. What does localhost:8080 mean?
  57. What is the difference between POST and PUT in HTTP?
  58. Download single files from GitHub
  59. HTTPS connections over proxy servers
  60. How to download a file over HTTP?
  61. Possible reason for NGINX 499 error codes
  62. Axios Delete request with body and headers?
  63. Get the full URL in PHP
  64. HTTP GET request in JavaScript?
  65. PHP + curl, HTTP POST sample code?
  66. Response to preflight request doesn’t pass access control check
  67. How to download HTTP directory with all files and sub-directories as they appear on the online files/folders list?
  68. What could cause “connect ETIMEDOUT” error when the URL is working in browser?
  69. What is HTTPD exactly?
  70. ./xx.py: line 1: import: command not found
  71. .htaccess Remove WWW from URL + Directories
  72. nodejs – first argument must be a string or Buffer – when using response.write with http.request
  73. Getting URL hash location, and using it in jQuery
  74. What is the meaning of ? (question mark) in a URL string?
  75. Check if a JavaScript string is a URL
  76. Serving HTTP and HTTPS from one installation
  77. If Modified Since HTTP Header
  78. How can I change HTTP headers only to posts of a specific category from a plugin
  79. http error when uploading media files
  80. Broken urls with http site and https wp-admin
  81. Can’t login to Dashboard when changing site URL to HTTPS
  82. 403 error on admin login page
  83. Is it possible to access the wp-admin from one instance while keeping WP_HOME pointing to the balancing url?
  84. wrong media url in wordpress
  85. Allow non-SSL pages to use https or Force non-SSL pages to http?
  86. Any any insecure http:// URLs left in wordpress?
  87. Implementing a URL Shortener
  88. How to convert srcset links from https to http?
  89. Local WordPress with WAMP downloads files out of Nowhere
  90. Reading URL Parameters
  91. Display values of current POST request on page
  92. Website Migration (with https) to a new domain(http)
  93. Understanding Redirects
  94. Staging Session Randomly Switched from Secure (https) to Not Secure
  95. Sudden Upload HTTP errors, PHP uploads and memory limits are already to high to my taste. Anything else?
  96. How to fix this CORS error?
  97. Why is http header providing 404 while site is online?
  98. Turn twitter-urls into list timelines?
  99. The plain HTTP request was sent to HTTPS port in wordpress [closed]
  100. Whole website redirected to httpa but in dashboard settings still http

Leave a Comment