You rely on your senses to tell you what is happening in the world around you. You see things, people, situation and happenings. You hear noises and words. You taste food and drink. You smell odours and scent. You feel and touch objects and surfaces. You are generally excited by something outside your skin and react to this stimulation by becoming aware of something which you were not aware of before. Sensation is the information obtained by the brain through sensory stimuli; this is a physiological process.
When you look at the world, those objects towards which you turn your eyes reflect light to you-you take in those reflection through your optical system. Cells of the retina react and send nerve impluse to optical nerves which send them as electrical impulse to the brain. Then the pattern of intensities and durations reconstruct a picture in your head of what you sensed before. The perception is the result of interpreting these sensory stimuli. This is a psychological process. Vision alone cannot account for the picture that you get of your world-you depend on very complex patterns of mental process of selecting, remembering, organising and interpreting.
Definition: Perception can be defined as the process of receiving, selecting, organizing interpreting, directing and reacting to sensory stimuli or data. It is the over all process of sensing and organizing sensory data into meaningful images.