Reiki level 1 (the subject of this post), is the basic level. Even at this level, you have life-long access to Reiki energy and the ability to use Reiki energy to heal yourself and others.

Essentially a Reiki Level 1 Attunement is a process that attunes you to the frequency of Reiki energy, enabling you to channel Reiki energy to yourself and others.
The Attunement is a type of ritual and kept secret by the Reiki master. The Reiki master will request students to keep eyes closed during the process. Some query the need for secrecy, but I think it is just a way to keep the process unique. Closed eyes make it easier to focus internally and enjoy the experience of the Attunement.
The Reiki master uses a combination of symbols and mantras to connect you to the Reiki universal life force.

Reiki Level 1 Lesson – Practice
You’ll feel much anticipation leading up to the Attunement, and although a relaxing process, it is quite a relief when it is over. The practice phase is more relaxed and quite fun. And it’ll give you the chance to feel Reiki energy for the first time.
The teacher will include Reiki meditations, which are useful for improving and maintaining the flow of Reiki. USUI Reiki meditations are listed here.
The channeling of Reiki energy is often compared to a water pipe or conduit. If not used for a while, the pipe blocks, constricting the flow. The meditations, along with regular use of Reiki, help with this.