There are a few characters that we use in HTML that need a special representation to be shown on a page.
Less than <
Greater than >
Ampersand &
Ampersand inception &
Semicolon just works ;
Money characters: £ € ¥
Math characters: ∑ ∀ ∈
Arrows: ← ↑ → ↓
The special characters can be in links: ♠♣♥♦