backward
In the direction behind you, opposite the way you face.
Backward means in the direction behind you, opposite to the way you're facing. When you take a step backward, you move away from what's in front of you. A backward glance means looking behind you to see what you're leaving behind.
The word can also describe doing something in reverse order. If you spell your name backward, you start with the last letter and work toward the first. Some people can recite the alphabet backward, starting with Z and ending at A. Reading a book backward would mean starting at the last page and flipping toward the beginning.
When describing a place or society, backward means undeveloped or behind the times. A backward village might lack modern conveniences like electricity or running water. This usage can sound judgmental, though, so people often choose more respectful terms like “developing” or “traditional” instead.
Backwards (with an 's') means exactly the same thing and is just as correct. Some people prefer one spelling over the other, but both work: you can fall backward or backwards, walk backward or backwards. Choose whichever sounds better to your ear.
There's also backward compatible, a tech term meaning new equipment works with older versions, and bend over backwards, an expression meaning to try extremely hard to help someone or make something work.