Unicode:
Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems.
An international encoding standard for use with different
languages and scripts, by which each letter, digit, or symbol is assigned a
unique numeric value that applies across different platforms and programs.
Unicode is a way of coding characters, replacing
the old ascii code.
Computers store data as numbers, even textual data. An encoding system, such as ASCII, assigns a number to each
letter, number or character. Operating systems include programs and fonts which
convert these numbers to letters visible on the screen and computer monitor.
Unicode, also known as UTF-8
or the "Universal Alphabet" is
a an ordered set of over a million characters covering the majority of writing
systems in the world. Unlike older systems, Unicode allows multiple writing
systems to co-exist in one data file. Systems which recognize Unicode can
consistently read and process data from many languages.
How do I create Unicode in
web pages?
There are several ways you can type or import Unicode text, but
each page must include a encoding meta tag specifying the utf-8 Unicode encoding, so that browsers render the text correctly. See
the code below:
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
...
</head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
...
</head>
Unicode is a character encoding standard that
has widespread acceptance. Microsoft software uses Unicode at its core. We are already using Unicode already!
Basically, “computers just deal with numbers. They store letters and other
characters by assigning a number for each one. Before Unicode was invented,
there were hundreds of different encoding systems for assigning these numbers.
No single encoding could contain enough characters.1” This has been the
problem If you are using a legacy
encoding your font conflicts with the font someone in another area of the world
uses.
URI:
a uniform resource identifier (URI) is a string of characters used to identify a name of a resource.
A uniform resource name (URN) functions like a person's name, while a uniform resource locator (URL) resembles that person's street address. In other words: the URN defines an item's identity, while the URL provides a method for finding it.
Difference
between URL, URI and URN ?
All
three URI, URL and URN are used to identify
any resource or name in internet but there is subtle difference between them.
URI is super set of both URL and URN. By the way main difference between URL and URI is protocol to retrieve the resource. URL always
include a network protocol e.g. http, https, ftp etc to retrieve
resource from its location. While URI, in case of URN just uniquely identifies
the resource e.g. ISBN numbers which are good example of URN is used to identify any book
uniquely.
URI
stands for Uniform Resource Identifier. URI is a text which is used to identify
any resource or name in Internet. URI has two specialization in form of URL (Uniform Resource Locator) and URN (Uniform Resource Name) to identify
resource and name.
A URL is a type of
URI that's used to describe the location of a specific document. A URL doesn't
define the type of content to be found (texts, images, movies, etc.); it only
says where and how to find it. A common URL is composed by four parts:
The protocol: Also
called URL scheme, this specifies which protocol is used to access the
document.
The computer name:
Gives the name of the computer (usually a domain name or IP address) where the
content is hosted.
The directories
path: Secuence of directories separated by slashes that define the path to
follow to reach the document.
The file name: The
name of the file containing the resource.
This way we can
analyze and split any given URL. For example, let's take a look at the URL of
the HTMLspan element (http://www.htmlquick.com/reference/tags/span.html):
Protocol: http://
Computer name (domain name):
www.htmlquick.com
Directories path: /reference/tags/
File name: span.html
URN:
URN stands for Uniform Resource Name. URN is also subset of URI.
One of the best example of URN is ISBN number which is used to
uniquely identify a book.
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All of these Examples
are URIs:
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Examples of URLs:
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mailto:someone@example.com
http://www.damnhandy.com/ https://github.com/afs/TDB-BDB.git file:///home/someuser/somefile.txt |
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Examples of URNs:
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urn:mpeg:mpeg7:schema:2001urn:isbn:0451450523
urn:sha1:YNCKHTQCWBTRNJIV4WNAE52SJUQCZO5C urn:uuid:6e8bc430-9c3a-11d9-9669-0800200c9a66 |
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