Red Roses:
Red roses are not only a symbol of love, a mere friend can send them, drawing attention to the beauty and respect that bring you together. It is one of the most exciting and passionate colors in a rose.

Mainly, red roses are a symbol of love, over all, young lovers choose them to give to their partners, but they can also be employed as a gift to a friend to show respect.

White Roses:
They are a symbol of purity and innocence.  Normally, it is the color chosen by brides for their bouquet on their wedding day because it signifies lasting their whole life. White roses are also united with love.  A couple who gives this type of rose wants to demonstrate the hope for a solid future together.  It signifies pure, happy, and everlasting love.

Also, if a person is sick, this is the color the flower should be to show that you are waiting on them.

Pink Roses:
Giving a pink flower is the way, through flowers, to thank someone for a big favor. It also signifies the appreciation you have for someone.  Pink carries the meaning of the absence of ill will, that is to say, there is no double intention in the person offering them.  Therefore, the person who gives this bouquet is trustworthy.  If the color of the bouquet of flowers is light pink, it signifies admiration and like.

Yellow Roses:

This is usually the ideal rose to give to an adolescent. For the more superstitious, this color brings warning with it.  If the person giving the flowers is not very close, there may be an ulterior motive behind the smile.  However, for the more skeptical people, yellow roses mean satisfaction and happiness and are a good way to celebrate a birthday or a significant day between friends.

Other colors:

Orange roses: denote enthusiasm and passionate desire.
Bordeaux roses: signify beauty unaware.
Blue roses: mean confidence, reserve, harmony and affection.
Green roses: mean hope, youthful rest and equilibrium.
Violet roses: give the understanding of calm, self-control, dignity and aristocracy.
Black roses: signify separation, sadness, death and night.
Gray roses: signify discontentment, boredom and age.