How do I write special characters like punctuation, symbols, emoji, and accented or "foreign" characters?

These characters can be written using HTML entity syntax. For example, an en-dash can be written using – , and a Euro currency symbol can be written using € . W3 Schools has an  HTML Punctuation reference list.

Unicode characters can be added directly. An easy option for emoji is to copy and paste from getemoji.com. Here's a smiley face. 😀

Similarly, you can copy any Unicode character from unicode-table.com. Here's a Mathematical Italic Small Pi. 𝜋