Plants that produce flowers are called flowering plants, or angiosperms.  Not all kinds of plants are thus classified; for example, ferns produce spores rather than flowers and are therefore not classified as angiosperms.
Flowers, besides their botanical function, are often prized by humans for their beauty. Many plants have been selectively bred to produce flowers with great appeal to us. Perhaps the rose is the best example of this.
Flowers are often a traditional part of important occasions such as weddings, funerals and graduations. They are often given to celebrate a happy occasion or given as a "thank you" or housewarming gift, or to cheer up someone in the hospital. It is traditional to give flowers on holidays including Valentine's Day, Mother's Day and on birthdays.There are also many well known pictures of flowers by famous painters such as Claude Monet and Paul Cézanne.