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URI-And-URL.md

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URI-And-URL.md

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tags
URL
Uniform-Resource-Locator
URI
Uniform-Resource-Identifier
Protocol
Domain
Subdomain
Port
Semantic-URL

URI-And-URL

URL stands for Uniform Resource Locators and it is a sub-category of URI (Uniform Resource Identifier). Each URL points to a single, unique resource. (An exception is when the linked resource does not exist anymore). A URL is like an #Address, it provides the full information to find a specific place/resource.

Components

Protocol/Scheme

Tell the protocol to be used for the request, some examples are:

  • #HTTP
  • #HTTPS: Which is a secure version of the #HTTP protocol, it is also the default protocol used if none is specified.
  • #data
  • #mailto It is usually followed up with :// or just :, for example http:// or mailto:.

Domain/Authority

Domain name that masks the underlying machines #IP in a human readable address. The domain is composed in different parts:

  • #TLD or #Top-Level-Domain: for example .com, .org or .net
  • #Label: is the #Secondary-Level-Domain or #SLD

Subdomain

A subdomain is a subsection of the Domain, for example google.com is the domain, whilst mail.google.com is an email-related subdomain.

Port

Optional component. The domain can also contain a #Port, which indicates the the specific "gate" to be used, when referencing a web resource, it is usually implicit as the #Web-Server already knows that an #HTTP request points to port 80, while a #HTTPS request point to port 443, otherwise it is mandatory.

Path

  • Absolute
  • Relative: works when referenced within the document

Parameters

Optional component. Extra parameters to provide some extra information to the request.

Anchor

Optional component. Useful for referencing sections within the same document. It kinda works like a bookmark. and it is used with an #, for example [[URI-And-URL#Anchor]].

Absolute vs Relative

URLs can be either:

  • Absolute: when the URL contains all the components needed to locate the resource, for example https://www.google.com
  • Relative: when the missing components get inferred based on the current page.
    • Scheme-relative URL: when only the scheme is missing //google.com
    • Domain-relative URL: when the scheme and domain are missing /index.html
    • Sub-resource For relative URL navigation the same logic of a #UNIX path is applied (where . indicates the current directory, .. one directory up and so on...).

Semantic URLs

Semantic URLs are URLs that abstract away the technical components and only keep the main components, making them easier to use and remember. For example google.com/search/puppies is a #Semantic-URL whereas google.com/?s=puppies is not. (EXAMPLE MIGHT NOT WORK BUT ILLUSTRATES THE CONCEPT).