Does every browser support all unicode?

Question

I want to reduce the number of HTTP-requests by using Unicode instead of small image icons.

The icons I'd like to use include ✔ ,► ,etc.

For a complete list of all required characters, see here

• Do all browsers support these characters by default?
• If not supported by default, can I add support for these characters?
• Which CSS and HTML are required to add these characters to a web page in a cross-browser way?

Also, I am making a Unicode website that makes use of the following language:

यो भाषामा म वेबसाईट बनाउँदै छु 

• Is it possible to get this language to be seen on every browser and every operating system?
• If it is possible to provide this support, which CSS and HTML code are required for this?
• Do I need to include a webfont for this?
• Which webfonts can I use and how do I add them in a cross-browser way?

Answer 1

This is a problem of fonts, not browser support. Barring serious bugs in a browser itself, as long as the user has a font installed with the character you're trying to use, it should display without issue.

Now, the intersection of all the glyphs in all the fonts built into every common operating system is a different question entirely and one that's a little more difficult to answer.

In the case of the small icons, the most reliable solution is to use the CSS @font-face rule to ask the browser to download a particular font. Then you'll know for sure that the user has an appropriate font installed. There are even some fonts designed specifically for this use, with extra icons built in: "Font Awesome" is a well-known example.

In the case of foreign text: presumably your audience consists of people who can read the script, right? In that case they almost certainly have font support already—many of them may have their entire interface in the same language!