as with most modern things - the answer is "it depends".
Pretty much all movies from the beginning of time were filmed in a "wide screen" format.
And all television broadcasts were done in the normal tv screen format.
On the older televisions, movies were almost always cut off on the sides to fit the odd shaped tv screen.
You just lost the edges.
Some older recordings of movies - instead of cutting anything off - they shrank the entire picture to fit the standard television screen so you can see the full image.
Of course, this left open areas at the top and bottom (the black bars)- so you could get the entire movie image.
That was what they used to call "letter box" due to it's shape - like looking through a mail slot.
now that our tv screens match the movie screens more accurately - there's no need to cut movie images off - but many broadcast stations still have to broadcast to "normal" TV's - so you end up getting a messy mix of options.
Your tv will have some sort of "aspect" button that can try to adjust for them on an as needed basis. On the Samsung I think it's "p.size"
You might want full width movies to take up your full screen - but if you watch a regular broadcast show like this - it'll be stretched out to fit. You want to go down to that mode so it looks normal (but you'll have black bars on the SIDES of the image). OR you can just zoom in on that image and it'll expand to fit the full screen, but you'll lose the top and bottom portions of the image.
it all makes sense once you play around with it for a while.
Every source will be different - just cycle through all the modes for every program and you'll get it.
Samsung makes a great tv - so if you're having any trouble, it's YOU not the tv. : )
- and to further confuse matters - many cable boxes have a similar function to alter the image size/aspect ratio before it gets to the tv - so be aware of that too.