type="color" opens a color picker and returns a hex value. type="search" is a text box styled as search (with a clear button in some browsers). type="tel" shows a phone keypad on mobile. type="hidden" carries a value the user never sees — useful for tokens and ids.
None of these are essential, but each adds polish or solves a specific problem more cleanly than a plain text box.
<!doctype html>
<html><head><meta charset="utf-8"></head>
<body style="background:#06040d;color:#e6e0ff;font-family:sans-serif;padding:20px">
<form action="#">
<p><label>pick <input type="color" value="#b388ff"></label></p>
<p><label>find <input type="search" placeholder="search…"></label></p>
<input type="hidden" name="token" value="abc123">
<button>submit</button>
</form>
</body></html>