What kind of special character is this: ?

There are many Unicode-lookup websites; the one I use is Uniview by Richard Ishida of the W3C.

If you paste your text into the box on that page and click on the down arrow, it shows you each character:

screenshot from Uniview

…and you can click on each character for more information. There are also a lot of other features; you can explore for yourself.

The characters in “ ” are:

  • U+1D4F1 MATHEMATICAL BOLD SCRIPT SMALL H, encoded in UTF-8 as F0 9D 93 B1
  • U+1D486 MATHEMATICAL BOLD ITALIC SMALL E, encoded in UTF-8 as F0 9D 92 86
  • U+1D4EA MATHEMATICAL BOLD SCRIPT SMALL A, encoded in UTF-8 as F0 9D 93 AA
  • U+1D4FF MATHEMATICAL BOLD SCRIPT SMALL V, encoded in UTF-8 as F0 9D 93 BF
  • U+1D486 MATHEMATICAL BOLD ITALIC SMALL E, encoded in UTF-8 as F0 9D 92 86
  • U+1D4F7 MATHEMATICAL BOLD SCRIPT SMALL N, encoded in UTF-8 as F0 9D 93 B7
  • U+1D4FC MATHEMATICAL BOLD SCRIPT SMALL S, encoded in UTF-8 as F0 9D 93 BC
  • U+0020 SPACE, encoded in UTF-8 as 20
  • U+1D4F0 MATHEMATICAL BOLD SCRIPT SMALL G, encoded in UTF-8 as F0 9D 93 B0
  • U+1D4EA MATHEMATICAL BOLD SCRIPT SMALL A, encoded in UTF-8 as F0 9D 93 AA
  • U+1D4FD MATHEMATICAL BOLD SCRIPT SMALL T, encoded in UTF-8 as F0 9D 93 BD
  • U+1D486 MATHEMATICAL BOLD ITALIC SMALL E, encoded in UTF-8 as F0 9D 92 86

Those are characters from the “Mathematical Alphanumeric Symbols” block. For example, the :

Mathematical Bold Italic Small E
U+1D486

:

Mathematical Bold Script Small T
U+1D4FD

In mathematics, you often see those kind of “script” letters.