I love felting fibers because the result is a surprise every time. There is great variability in the balance of control between artist and fiber.
In felting, very simple materials are needed – fibers (especially wool), mild soap, water, and a textured surface like bubble wrap. Depending on the method, barbed needles, foam rollers, wooden brushes and other tools are used as well.
There are a number of ways to manipulate fibers to make felted objects. Below are two short and quick visual descriptions of ways that I work with wool to felt.

When wet felting you generally work on a flat surface and carefully layer fibers onto each other – often around a template. The template gives a rough starting point for the final shape of the object (hat, vessel, flower, etc.)

When needle/wet felting you typically start by poking bits of fiber into a dense foam shape, alternating directions and several layers thick. This is them carefully removed and taken through the wet felting stages of soaping, kneading, rinsing, rolling and shaping before it reaches its final shape.

Beyond crafting pieces for people to enjoy, making felted goods has the additional bonus that it is excellent for stress management! You get to repeatedly poke things with barbed metal needles and throw felt at the ground as hard as you can- on purpose.
People have been making felted goods for centuries all over the world. These are just the methods I have discovered so far. I am excited to see what comes next!