URL Encoding (The "%20" codes in Sharepoint URLs)

How are characters URL encoded?

URL encoding of a character consists of a "%" symbol, followed by the two-digit hexadecimal representation (case-insensitive) of the ISO-Latin code point for the character.

Example

            Space = decimal code point 32 in the ISO-Latin set.

            32 decimal = 20 in hexadecimal

            The URL encoded representation will be "%20"

Unsafe characters

Why: Some characters present the possibility of being misunderstood within URLs for various reasons. These characters should also always be encoded

Character	Code Points (Hex)	Code Points (Dec)	Why encode?
Space	20	32	Significant sequences of spaces may be lost in some uses (especially multiple spaces)
Quotation marks 'Less Than' symbol ("<") 'Greater Than' symbol (">")	22 3C 3E	34 60 62	These characters are often used to delimit URLs in plain text.
'Pound' character ("#")	23	35	This is used in URLs to indicate where a fragment identifier (bookmarks/anchors in HTML) begins.
Percent character ("%")	25	37	This is used to URL encode/escape other characters, so it should itself also be encoded.
Misc. characters:    Left Curly Brace ("{")    Right Curly Brace ("}")    Vertical Bar/Pipe ("|")    Backslash ("\")    Caret ("^")    Tilde ("~")    Left Square Bracket ("[")    Right Square Bracket ("]")    Grave Accent ("`")	7B 7D 7C 5C 5E 7E 5B 5D 60	123 125 124 92 94 126 91 93 96	Some systems can possibly modify these characters.

Reserved characters

Why: URLs use some characters for special use in defining their syntax. When these characters are not used in their special role inside a URL, they need to be encoded.

Character	Code Points (Hex)	Code Points (Dec)
Dollar ("$")  Ampersand ("&")  Plus ("+")  Comma (",")  Forward slash/Virgule ("/")  Colon (":")  Semi-colon (";")  Equals ("=")  Question mark ("?")  'At' symbol ("@")	24 26 2B 2C 2F 3A 3B 3D 3F 40	36 38 43 44 47 58 59 61 63 64