Most every culture in the entire world has a version of it.
It must be important, then right?

It has many meanings, all depending on who is using it. But it is just a word, a label, in Buddhist terms. The techniques are very different between different cultures but the idea is roughly the same.

Synonyms: contemplation, thought, thinking, musing, pondering, consideration, reflection, deliberation, rumination, brooding, reverie, brown study, concentration and a lot more. (Source: Google)

Definition of

meditated; meditating

Intransitive verb
1 : to engage in contemplation or reflection He meditated long and hard before announcing his decision.
2 : to engage in mental exercise (such as concentration on one's breathing or repetition of a mantra) for the purpose of reaching a heightened level of spiritual awareness

Transitive verb
1 : to focus one's thoughts on : reflect on or ponder over He was meditating his past achievements.
2 : to plan or project in the mind : intend, purpose He was meditating revenge.
(Source: Merriam Webster)

Judeo-Christians:
Meditation is a combination of Prayer and Contemplation. Prayer being very spiritual in nature while contemplation is a period of conscious thought concerning a spiritual topic. So prayer is similar to that of reciting mantras and contemplation is a type of analytical meditation. The main connection of these is that of concentration.

Hinduism:
Yogic meditation is a very similar practice. It involves a conservative practice at its finest. It is a practice of single pointedness of the mind similar to Buddhism where one must focus the mind on a single object which could include a physical object, image or even a syllable from a chant. This practice is meant to be increased in difficulty with more complexity over time.

Buddhism:
Concentration is the most valued of practices. Through meditation, concentration, one must become aware of ones self. Build this state of awareness. There are many different types of meditation in different sects of Buddhism. Here are just a few:

• Zen Meditation is based on sitting (ZaZen). The goal is to meditate and become aware. It is a simple idea but yet very difficult to fully benefit. Zen does this by two different means. The first is to just dive right into meditation and the second is to trick the mind into reaching this state of awareness (Rinzai school of teaching). The latter can be accomplished by the student being in a situation with a lot of stress and one that seems unaccomplishable.
• Tantric Meditation is a practice where one must remove the ego. Removing this idea of "I" or "Me." It is believed that this hinders being fully aware. The way this is approached is through visualizations. The person is to become a deity from an image or teaching and separate themselves from their self-concept.
• Vipassana is one of the oldest practices and it originates from the scriptures of Satipatthana Sutta. Supposedly direct teachings of the Buddha himself. The cultivation of mindfulness(awareness) is meant to be gradual and direct in this method. Gentle but thorough its technique is a step by step process of noticing ones existence over time. In it we learn to actually sense what is around us. We learn to examine our thoughts without being attached. Ultimetly we are to learn impermanence, unsatisfactoriness and compassion (selflessness). It teaches that what we know now is delusion. In Pali it is vipassana bhavana, or seeing ourselves in a new way. Really just Insight or full understanding. It is known as "Insight Meditation."

Sikhism:
In Sikhism, meditation is about bringing all the thoughts to only one thought of the CREATOR. We have to get rid of the thoughts such as bondage, lust, greed, anxiety and fear by chanting and LISTENING to the word "Wahe - Guru". Once we reached at "thoughtless" stage, there are chances to open the "10th gate" or "Crown Chakra" and we wait there to be called by The Creator. For Sikhism Meditation is a way to move near the Creator, but not a guarantee to meet the Creator "if this is so then our meditation is bigger than The Creator and which can never be". We do meditation to get rid of our thought at our will and go to sit in front of Creator's doors and then it's the Creator's Mercy or Kindness when we get a call!
To learn more about Sikhism, following site can be visited: Mysimran.info
(Sikhism by: @mathworksheets)

The Buddhist meditation practices are among the oldest of all religions. Buddhism is around 2,500 years old. Compare that to other western religions. Do you know how old Christianity is? Hint: consider BC and AC.

Please make note below with your experiences with different types of meditation. Which have you used? Which have helped you? How long have you practiced this and how often?

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NAMASTE ( BOW ) and Thank you for reading, @nicnas