There's mindfulness meditation which is about simply focusing on and observing what is going on in the present moment without changing anything. It is simply the perceptual mode of observation when one's thoughts are quiet as one's attention to directed fully to the immediate.

There's perception bending of various sorts which is about seeking to modify present perception with a desired and/or anticipated perception to create self-induced hallucinations: https://pastebin.com/vHKeTau2 It is the inverse of mindfulness. Various kinds of "energy work" involve creating tactile hallucinations which can be as experientially intense as any physical sensation, leading to the error of mistaking the sensations as corresponding to some kind of vital energy. Inducing mystical experiences, including in a group ritual setting, is perception bending.

There's also daydreaming, and when one devotes their attention entirely to the task of intentionally daydreaming it absolutely qualifies as a form of meditation, and is the most common. One plays out scenarios in their head, recollects memories, plans and wonders. Daydream is nothing less than the task of weaving one's soul, which is why humans devote a great deal of time to it (30-50% of waking hours.) Daydreaming combines the self-induced hallucinations of perception-bending with the lack of goal-direction of mindfulness meditation (one's thoughts wander from subject to subject, following tangents and involvements in an exploratory, improvisory way, instead of forcing the intensity of a particular perceptual experience.)