Spiritual enlightenment is the fundamental goal of most spiritual practices that you undertake. Enlightenment marks the culminating point of your practice you feel unity of soul with everything, all the mental and physical engagements are left aside. Spiritual enlightenment is the possession of highly evolved souls.  Spiritual masters from all over over the world experience spiritual enlightenment, and help others on there own paths.

Spiritual enlightenment is often categorized into levels for practical purposes. The highest stage of spiritual enlightenment marks the attainment of unity with God or being one with everything.  But  can still there are certain levels through which the individual needs to evolve. In a similar way that man has evolved from more primitive animals, the human concisiness or soul also evolves.  For our practical purpose, put them in stages and analyze the state of being in each stage:

The first stage of spiritual enlightenment
At the very first level of enlightenment, the individual starts experiencing reality as it is. It means that your mind ceases to interfere with what you are experiencing.  We are engaged in continuous talk, gossip, analyzing the environment around us, planning about future, or worrying about the past.  When you are in a state of spiritual enlightenment you are completely in the present moment.  You stop judging and labeling the world.  Your mind is calm, quite and still. You are very awake, and aware of the current moment right now.

The second stage of spiritual enlightenment
At the second stage of enlightenment, you feel apart of yourself in everything around you. You feel  a connection with every object and individual in the world. The borders between yourself and the world around you dissipate. Your soul begins to merge with Supreme Soul. You feel that you are not individual anymore and not separate from anything. You feel that you are in everything and everything is just a part of the Supreme Soul from where you also have emerged. Many people describe this feelings of completeness and love.

The third stage of spiritual enlightenment
The third stage of enlightenment, you no longer feel connected to everything but realize you are everything.  You the experience the oneness of God and are not separate from anything in the universe. This stage of enlightenment is a direct experience of oneness.

Spiritual enlightenment is the fruit that sets you free, as you lose all wants and wishes to receive the fruits of your actions. You feel the bliss of completeness and true love. At first it gives you the feeling that you need "Light". At the next stage, you feel that you are merging in "Light". And in the final stage you and the "Light" are one.