Question

which material are required to write a letter with invisible letter and how can we read it​

Answer 1

$\huge\fbox\colorbox{silver}{❥Answer♡}$

Invisible ink is any substance that you can use to write a message that is invisible until the ink is revealed. You write your message with the ink using a cotton swab, dampened finger, fountain pen, or toothpick. Let the message dry.