What is the meaning of the lotus? On the altar when entering a Buddhist temple I see the Buddha sitting on a lotus, but frankly I do not understand the symbolic meaning of the lotus image? Everywhere you look in the temple you see lotuses. Can anyone explain this to us?
Well there are more than one meaning to the lotus image. It is a multi-layered symbol.

http://buddhists.org/buddhist-symbols/the-meaning-of-the-lotus-flower-in-buddhism/
the meaning of the muddy waters, physicality being the ground out of which the nirvana experience grows.


  The lotus flower represents one symbol of fortune in Buddhism. It
  grows in muddy water, and it is this environment that gives forth the
  flower’s first and most literal meaning: rising and blooming above the
  murk to achieve enlightenment.


and the second meaning refers to how the pure flower is when its roots are in the mud and the earth


  The second meaning, which is related to the first is purification. It
  resembles the purifying of the spirit which is born into murkiness.


Rather than faithfulness to a doctrine, what it implies is faith in the process so that at all points of development from a shoot out of the mud, to blooming, it is the process of awakening.
The third meaning refers to faithfulness. Those who are working to rise above the muddy waters will need to be faithful followers [of the process] (note added by soulsings)

Each color implies a different quality of the buddha mind.


  The color bears importance in the meaning of the lotus flower in
  Buddhism. A white lotus flower refers to purity of the mind and the
  spirit. If a lotus flower is red, it refers to compassion and love.
  The blue lotus flower refers to the common sense; it uses wisdom and
  logic to create enlightenment. The pink lotus flower represents the
  history of Buddha and the historical legends of the Buddha. A purple
  lotus flower speaks of spirituality and mysticism. Finally, the gold
  lotus flower represents all achievement of all enlightenment,
  especially in the Buddha.
  and regarding colors also see 
  http://www.buddhanet.net/e-learning/history/b_lotus.htm


and the symbolism of the stages of growth.


  The stage of growth the lotus flower is in represents a different
  stage of enlightenment. A closed lotus flower represents the time
  before a Buddhist follower found Buddha or enlightenment. A lotus
  flower fully bloomed and open represents full enlightenment and
  self-awareness.


Rising out of the mud of materiality into the emotions (represented by the water)
the path of awakening eventually leads to the opening of the lotus flower before the sun of compassion and wisdom.