What is a silhouette? Is it defined as a shadow? Where does the light come from?
One definition is that a silhouette is a subject that is backlit and it is viewed from the dark side in contrast to a shadow where the form of an object is cast on another surface.
A silhouette creates mood or mystery.
So how can this be done?
The easiest way is in Manual mode on your camera:
Sitting in your kitchen with big windows on a bright sunny day.
Outside (unless you have an amazing skylight) will be a lot brighter than inside. You will be able to tell this when you see your light meter shoot to plus 1, 2 or 3 when pointed outside and minus when you turn your camera to inside of the kitchen.
Then go to your kitchen window and expose (get your light meter to zero) on the scenery outside. Tip: make sure that part of the background will be in your composition.
KEEP that exposure. You can let go of all the buttons and dials. This is manual mode only your light meter inside is moving up and down.
Place your subject a meter away from the window.
What does your light meter say now? It will say Minus but DON’T correct it.
As that is what you want it to say. It is underexposing.
Lock focus on your subject or wherever you want the sharpest part to be and your subject will be a Silhouette.
Choose a subject that is interesting and shows strong features in the image.
If you are not using manual mode on your camera, the on camera flash might keep popping up- Turn it off.
Spend time getting your light right and checking your exposure.
Compose your image.
If you would like some detail of your subject or a little hair-light you can move the subject closer to the window where some light will fall on them. This gives a three – dimensional feel and is used in Studio lighting.