Text format specifications:

Escape chars:
\&
\[
\}
\\

Color and format codes:
&a, &k, &r, etc.
- § also supported
- reset format when changing color as per motd

Click events:
[open_url | run_command | suggest_command | change_page | copy_to_clipboard]{<unformatted value>}(<affected text>)

Hover events:
[show_text]{<text formatted value>}(<affected text>)
[show_item]{<optional slot id; default selected hotbar slot, else air>}(<affected text>)
[show_entity]{<optional uuid; default entity looking at, else self>}(<affected text>)

Example:
Red text followed by clickable and hoverable green text followed by gold text

&cRed text [run_command]{/say clicked!}([show_text]{&6Try me!}(&aGreen text)) &6Gold Text