I used some good looking ones from http://dev.w3.org/html5/html-author/charref on my site but I just noticed that they don't show on mobile browsers of Android.
For example:
⪦⪢Which special characters and HTML Character Codes (entities) have crossbrowser/crossplatform support?
The named character references added in HTML5 do not work cross-browser, though the support is relatively widespread now. Generally, there is hardly ever any reason to use them (as opposite to references defined in HTML 4.1, which are well supported).
Quite independently of this, the characters themselves (no matter whether entered as such, as named references, or as numeric references) need to exist in some font in the system and the browser needs to know how to find them. There is no list of characters with crossbrowser/crossplatform support, since each system has its own fonts and many browsers have specialities in using fonts.
To make characters appear in (almost) all systems, you would need to use web fonts (downloadable fonts), which come with problems of their own. See my Guide to using special characters in HTML.
Using these two web resources find out about browser support for any html character entity. Like if you need to choose between ≈ ≈ ≈ for ≈
https://code.google.com/p/doctype-mirror/wiki/AsympCharacterEntity
It depends on your font. Choose one that supports all the Greek characters a good policy. Go to Google Fonts to find a good one.
Since a while back, last century, around Netscape Navigator 3.0 let's say there was basically three fonts I think:
Times New Roman, serif
Courier, fixed
Arial, sans
At some point later Verdana sans became widespread (late 1990's).
Then nothing...... in 1999 Shigetaka Kurita invented Emoiji for NTT DoCoMo in Japan.
Desperate designers began using flash and "Swiffobject" text replacement which sucked.
It was getting pretty messy then Google thankfully launched G Fonts library in 2010. You can see on their analytics page, the most popular font today is Open Sans with 4 trillion views in a year wow. https://fonts.google.com/analytics
