The basic idea generally associated with why people meditate is that during our day we are constantly subjected to sensory input and our minds are always active in the process of thinking. We read the newspaper, study books, surf on internet, read news from websites, search anything from search engine, write reports, engage in conversation, solve problems... Typically, as we do these normal activities we engage in a constant mental commentary. People aren't fully aware of all the mental thought activity that we are constantly engaged in.
Meditation allows all this activity to settle down, and often results in the mind becoming more peaceful, calm and focused. In essence, meditation allows the awareness to become 'rejuvenated'.
Meditation can be considered a technique, or practice. It usually involves concentrating on an object, such as a flower, a candle, a sound or word, or the breath. Over time, the number of random thoughts occuring diminishes. More importantly, your attachment to these thoughts, and your identification with them, progressively become less.
The entire process of meditation usually entails the three stages of concentration (dharana), meditation (dhyana) and enlightenment or absorption (samadhi). The individual preparing to meditate usually starts off by harnessing his awareness, such as focussing his mind onto a certain object. Once attention gets engaged, concentration turns into meditation or dhyana. And through continuous meditation, the meditator merges with the object of concentration, which might either be the present moment or the Divine Entity.
Experiences during meditation probably vary significantly from one individual to another, or at least if different techniques are involved. Relaxation, increased awareness, mental focus and clarity, and a sense of peace are the most common by-products of meditation. While much has been written about the benefits of meditation, the best attitude is not to have any expectations when practicing.
In some branches of Indian philosopohy, direct perception from the inner self (mana) together with perception that is filtered through the five senses (pancha indriya) form a part of their valid epistemology (pratyaksha jnana). And this self-realization or self-awareness (as popularized by Paramahansa Yogananda), is nothing but the knowledge of the "pure being"—the Self. Humanity is increasingly turning towards various meditative techniques in order to cope with the increasing stress of modern-day lifestyles.
The state of relaxation and the altered state of consciousness—both induced by meditation—are especially effective in psychotherapy. But more than anything else, meditation is being used as a personal growth device these days—for inculcating a more positive attitude towards life at large.
