Vector quantity question: What is unit vector?

Please explain what is this UNIT VECTOR , what is its use, how it is used and what is î, ĵ, k^? I know the definition already: "It is the vector whose magnitude is 1" but I didn't understand what it means, how can you say that the magnitude of every unit vector is 1?? Isn't it written as A = 3î... show more Please explain what is this UNIT VECTOR , what is its use, how it is used and what is î, ĵ, k^?
I know the definition already: "It is the vector whose magnitude is 1" but I didn't understand what it means, how can you say that the magnitude of every unit vector is 1??
Isn't it written as A = 3î +6ĵ+ 4k^? then how is its value 1?

I am confused, so long explanations are better.
Thanks for answering!
3 answers 3