Your brain is composed of millions of brain cells. When these cells, called neurons, communicate an enormous electrical activity is produced in the brain. This electrical activity produces brainwaves. The frequency of these waves influence our state of consciousness.
Beta or the most effective brainwave frequency for physical activity such as executing a plan, relates to the state of outward concentration. The Alpha frequencies are too within our reach by the virtue of daydreaming, as this is the state we attain after we have just woken up from sleep, and it is a transit between waking and sleeping stages. Increased levels of Alpha brainwaves, yields a relaxed body and mind, higher levels of creativity, positive thinking and a peak performance. Theta band has been known to facilitate super-learning, kids of age 5-8 years spend a lot of their waking time in theta, no wonder they are pretty fast learners. People with high amounts of delta brainwave have been found to have increased empathy and access to the unconscious mind.
The useful frequencies in alpha, theta or delta stage are not usually in accessible to us consciously, i.e. we do move through these three states as well but only during sleep or near sleep for relaxation purposes.
So, now the big question popping up in your head or better, brain is, how do we access these states of brain, consciously? There are various ways to do that too, all around us, some are known to us but we usually shy away from even trying them. But the easiest one and that involves technology is called Brainwave entrainment. This involves using auditory and visual stimuli to affect your state of mind. Brainwave entrainment works on the phenomenon of Frequency Following Response. This phenomenon explained in simple terms is the ability of human brain to respond to particular beat of visual or auditory stimuli and follow it, that means if we apply a stimulus of 6Hz of sound then the brain will start attuning to this frequency and start generating theta brainwaves within about 6 minutes of the constant stimulus.
A few softwares you can try out for the purpose are Neuro programmer, Mind Workstation and Natura Sound Therapy.