1. It is a state after which there is no re birth.
2. It is a state where u become one with the supreme lord or you stay in his abode permanently
3. It can be attained if your virtues and vices total to zero. Means you should have zero karma result. If u have virtues you'll get its good results if u have vices you'll reap bad results. But when your karma result becomes zero you can attain moksha. So, do all the works (karmas) with detachment. offer the karma result to the lord and unattached yourself with its result.
4. Another easy way is, even if u do lot of sins in your life but at the time of death if you remember Vishnu/Shiva and leave your body your sins and good dead everything will get nullified and you'll instantly attain moksha .
The total energy always remains the same whenever energy changes from one form to another, even if the energy loses its ability to be used for performing work. This principle, the conservation of energy.
This clearly shows limitation of body, mind, brain. stages are there, everyone goes through it.
& only soal can merge with parmatma first find out source of that infinite energy bliss.
We choose path according to our will, everyone should have freedom for this divine goal.
Do not believe a thing because you have read of it in book or another said it is so! Find out the truth for yourself! That is the Realization.