There are many different meditation techniques which can be used, coming from a variety of different religious and spiritual traditions. However, meditation can be taken out of its religious/spiritual context and be used as a universal tool for us humans to discover the depths of who we are.
Different meditation techniques may have different objects of attention and may be used for a variety of purposes. Some meditational practices may be more of a relaxation exercise to prepare for deeper meditation e.g. relaxing our bodies and releasing our mental tensions. Some meditational practices may be more of a concentration technique, such as directing our attention on a particular object and focusing it on that object. The object of concentration could be the repetition of a sound, natural breathing, bodily sensations, a visual object, a point of attention within our body (e.g. in-between the forehead), amongst many others. Other meditational practices include visualizations, mindfulness meditation, contemplations, affirmations of our true nature, kriya meditation, devotional meditations, amongst many others.
As our meditation practice becomes more subtle and intuitive, we discover many aspects of our relative and absolute nature through insight.
You may use whatever technique you find beneficial, depending on what you wish to achieve from meditation. You may use relaxation techniques to relax the body-mind, concentration techniques to make the mind one pointed or just naturally be aware. Ultimately, meditation is used to go beyond just relaxation and concentration of the mind and to developing greater self awareness and insight.