Not at all.

ASCII is an encoding, a system where each character in a limited set is assigned an index number.
Due to unchecked growth, one is nowadays wise to ask "What kind of ASCII?" -- where possible answers range from 7-bit to ISO-8559, ISO Latin1, Windows Greek, Mac OS Roman, OEM (whatever that means -- it depends on the manufacturer), or any other 8-bit subset. (It just might be relatively safe to state 8-bit is closely linked to 'pure ASCII'.) Even EBDIC encoding, quite popular before ASCII became The Next Big Thing, exists in a few variants.

Domain names are abstract data, and so is source code, valid in ASCII encoding but also for example in EBDIC or in Unicode -- it gets translated to a convenient data format when it's interrogated. (An upcoming change in domain names is allowing almost the full Unicode set.)
Email servers send their header data in ASCII because the mail: protocol says it must. If some mail program does not internally 'work' with ASCII, it will internally convert the data to whatever it uses.

It's important for a 'coder' to know what kind of text files his compiler accepts (although some compilers may accept source files in different encodings). When fed with a text file with an unexpected encoding, the compiler will only see nonsense.

Generally, software worldwide is written to be able to handle at least 7-bit ASCII -- but it's just because you have to have some basic convention. Anything above and beyond 7-bit ASCII (and, when taken the interpretation of character codes 0..31 into account, anything in 7-bit ASCII as well) may produce unexpected results on different platforms, with different software.

Whatever ASCII is, it certainly is not a font, super or otherwise.

A modern font type such as TTF consists of a list of enumerated glyphs, where each glyph index means exactly nothing at all. Tables in the font file allow a translation from the font glyphs to at least one and usually several common encoding schemes, which is the responsibility of the font creator.

@Theunis de Jong
Though nice to have you respond, I am not satisfied. There is a super control / monopolistic aspect to ASCII system that can be seen by end users today. I had some arguments at IETF and Unicode Consortium a while ago. It is a not straightforward issue imho even though so called 'qualified' people say otherwise.

Maybe you should just come up with your own encoding then? You can even name it after yourself, and then try and convince people to use it.

Actually, that would not only be a very useful endeavor, but also so much fun.

"Thus ASCII is also superfont."

What?

.. There is a super control / monopolistic aspect to ASCII system that can be seen by end users today.

Correct. It's its one and big advantage -- it's called standardization. Without standardization (such as aforementioned ASCII protocol for e-mail headers), writing software would still be possible on a closed system, but communicating to other systems would be far more difficult.

A historical point: before MS-DOS (utilizing ASCII encoding for storing file names on disk), CP/M ruled -- not one singular version, but just about every computer manufacturer wrote its own. One of CP/M's biggest drawbacks was inter-computer communication: a disk written on one computer could only be read by specially written software.

Nowadays, with the World-Wide Web, computers need standards more than ever.

What Sebastian says: nothing prevents you from taking a note book, draw all of the characters you need on it, and assign a unique number to each one. Then you write an OS (computer operating system) that uses your encoding to read and write data to hard disk and removable media. Still no problem -- an Open Source OS such as a Linux variant can be altered at wish. But if you are planning an e-mail client, you'll need to make a table that converts your encoding to ASCII, and the reverse. The same goes for storing data on external media: if you store a text file on an USB stick (utilizing your own file name scheme), any other computer will not be able to read it. Even if you write a tool to be able to access the files, you still would not be able to open and read your file with Word -- for that, you'd need yet another conversion tool.

ASCII is an encoding standard that for historical reasons forms a subset of numerous other encoding standards, including Unicode.

It's certainly true that ASCII - and by that I mean the 7-bit code, not the 8-bit ISO 8859-1 - is what many computer systems were designed to work with. Originally, ASCII only was a 7-bit code, and computers in some European countries simply used a modified version of the 7-bit code, where less-used characters like { | } ~ were replaced by accented letters their languages needed.

This meant they weren't using ASCII any more, but they were still compliant with the ISO 646 (or ECMA 6, or International Telegraph Alphabet No. 5) code because those characters were in "national use" positions, similar to what existed for the 5-level code.

When the 8-bit code was developed, the first half matched the U.S. version of ITA 5, or ASCII, simply because that was the one in most common use. It's unfortunate that all languages can't have equal status, but Unicode, and the UTF-8 encoding of Unicode, have made it possible to use characters from other languages in many applications.

URLs of web sites, though, ought to be something anyone can type in from any computer. However, just recently, it has become possible for Chinese web sites to have URLs in Chinese characters, due to the adoption of new standards.

ASCII has letters and even ASCII art on the net uses fixed font.

I prefer having ASCII letter k/K to be another shape being क/क (there are height differences between lower and upper cases that can't be put by typing on this board software.)

Multilingual (not internationalised) domain names have not been possible so far as 2 or more language scripts are not allowed, e.g. http://www.booकs.com.

Internationalised domain names e.g. http://idn.icann.org/#The_example.test_names use punycode.

Latin/roman domain names use ASCII (not all) e.g. http://www.microsoft.com.

A possible solution for having more than 2 language scripts in a domain name would be to also use punycode (different sort: punicode2) for latin/roman domain names.

The words 'Multilingual' and 'Internationalised' with regard domain names have become confused and are used interchangeably. This needs to be corrected.

ASCII has letters and even ASCII art on the net uses fixed font.

You are confusing yourself, and everyone else, by using the terms ASCII and Font as if they are the same. There are plenty of fonts that Are Not ASCII at all.
"ASCII has letters" -- wrong. "ASCII defines a code for each character out of a limited set" -- better.
"ASCII art on the net uses fixed font" -- well, yeah. "ASCII art" is a term for a specific form of art, which needs a fixed font to be viewed properly, but other than its name is not inherently linked to ASCII. One can make "EBDIC art" as well (which, when viewed with an EBDIC aware editor, will look just like ASCII art). Presumably we'll going to see Unicode Art somewhere in the future.

Internationalised domain names e.g. http://idn.icann.org/#The_example.test_names use punycode.

As said before, ICANN is looking into allowing (almost) any Unicode character in domain names. You'll have to wait for that. I hope you can live with the fact that the actual DNS name is still encoded in ASCII characters.

Finally -- the crux of the heart of matter, so to speak:

I prefer having ASCII letter k/K to be another shape ..

ASCII characters don't have a shape. It's the font which you are using on your computer that dictates the shape of character for the Unicode U+004B (generally known as "LATIN CAPITAL LETTER K"). If you want to edit all of your fonts, replacing the glyph that defines the shape for the letter K with whatever you want.

Oddly, this entire discussion seems to boil down to the fact that you do not grasp the difference between ASCII (a specific encoding, endorsed by anyone with half a brain), the letter K (which has nothing to do with "ASCII" in the general sense that it's only one of the 96 default characters in that encoding set), and fonts in general.

As a footnote, I find the glyph घ (Devanagari letter Gha) vaguely disturbing. I feel like I'm sitting in a toilet bowl, looking up at just the wrong moment. Where can I protest against this glyph and request its removal from my computer?

@Theunis de Jong
I understand you are fast.