hand
Your hand is the part of your body at the end of your arm. It includes your fingers and your thumb.
Don't refer to a particular person's hand as ‘the hand’. Say his hand or her hand. You refer to your own hand as my hand.
The young man held a letter in his hand.
Louise was shading her eyes with her hand.
I raised my hand.
The guards put their hands on his shoulders and led him quickly away.
However, if you say that someone does something to someone else's hand, you usually use the.
I grabbed Carlos by the hand.
Ahmed took his wife by the hand.