Reiki is a brand of healing modality, and I use the term more or less synonymously with energy healing. As a Reiki Master, I've achieved the highest level of certification (before instructor), but in truth the training is unnecessary for anyone with a gift for healing. There is nothing special about Reiki. The important thing is the intention to heal, both the conscious intention, and who you are as a person. If you are someone who deeply cares about other people then you are a natural healer. And of course, like everything, practice makes perfect.
Traditionally Reiki and other forms of energy healing are done through the hands. The rise of the Internet popularized remote healing. Remote healing was always a thing, but it's now more common than the more traditional hands-on approach. It just so happens that remote healing tends to work better, which nobody really expected, and the only valid reason for which being that the hands were never necessary in the first place. It's particularly fascinating that energy seems to find its way to the intended recipient, even through phone calls or video chats. There is perhaps a clue there about the true nature of reality, and a warning for how closely we are connected to people we interact with, even when we think we are safely separated by space.
Energy healing operates on multiple levels, with most practitioners only reaching the first level. This first level focuses on healing the emotional layer of body by providing nourishing energy, allowing the emotional body to heal itself. This can be seen as a feminine approach, being non-invasive, supportive and intuitive. Subsequent levels alternate between feminine and masculine. The feminine levels promote growth and healing, while the masculine levels involve a more skilled (learned rather than intuitive), surgical approach. In these masculine levels, the healer identifies and carefully removes foreign entities such as parasites, hooks, and implants. As one progresses through these alternating levels of healing, each layer peels back to reveal and access deeper parts of the individual's soul.
For the most part, energy healing is a process that speeds up the natural healing of emotional and spritual wounds. But like always, the cause of the wound must first be resolved, else you will find the wound reopening shortly after.