URLs frequently use conflicting characters such as question marks “?”, ampersands “&”, hash “#” (i.e. pound or number sign), brackets “{}”, slashes “/\” and others.  You may have noticed the escaped hexadecimal ASCII representations of these symbols in a URL. For example, have you seen a %20 in a URL?  It stands for a space.  Or have you seen %3F?  It represents a question mark.  Most advanced webmasters do not use spaces in their URLs and instead use hyphens.  This is because they are trying to avoid the ugly look of a URL like example.org/about%20us, and instead use example.org/about-us.  In many cases webmasters do not intentionally use ugly URLs.  Many are derived through programming such as a search query or login, which often use a question mark and equal sign.  The following is the list of URL character codes for reference when translating ugly URLs.

<     %3C

>     %3E

#     %23

%     %25

{     %7B

}     %7D

|     %7C

\     %5C

^     %5E

~     %7E

[     %5B

]     %5D

`     %60

;     %3B

/     %2F

?     %3F

:     %3A

@     %40

=     %3D

&     %26

$     %24

+     %2B

"     %22

space %20

For more information go to w3schools.com.  Please comment below if you have any questions.