The word meditation carries different meanings in different contexts.
The term 'meditation' can refer to the state itself, as well as to practices or techniques employed to cultivate the state. Many studies on mindfulness have linked  alpha and theta  brain waves to meditation. Life conditions which require attention to multiple activities have a predominantly beta brain wave signature. 
In a meditative state a person is more relaxed but maintains a sharp awareness. It is a measurable activity. Meditation has been practiced since time immemorial, sometimes as a component of  religious traditions.
Meditation involves an internal effort to regulate the mind in some way. It can be used to clear the mind and to ease many health issues, such as high blood pressure, depression, and anxiety. There are many styles of meditation practice.It may be done sitting, laying or moving.
Meditation can be guided, focusing on a point of light or looking at a flame. Objects such as beads may be used during meditation. It may involve repeating a mantra or experiencing inner quiet. Meditation is a state of mind.