In a nutshell, ascended masters were once people walking around on earth, like you and me. Their souls passed through many lives (also known as embodiments or incarnations), working through karma, passing tests and fulfilling their unique reasons for being.
Finally they made it back home to God, passing through a ritual known as the ascension, which basically means they don't have to come back to earth anymore!
Some of them choose to come back - be born and go through the life cycle again - one or two further times, to try to help the rest of us in ways that are easiest to do when you have a physical body. But on the whole they are in a different plane of existence from the one that we are living in - a 'spiritual realm', if you will.
How Can Ascended Masters Help You?
As spiritual guides, ascended masters are simply invaluable. Not only do they have that 'been there, done that' advantage, they've actually gone above and beyond the sorts of daily challenges with which we'd like help. They've reached the ultimate goal that our souls are striving for (whether we know it on the outer or not). They have a perspective that spans infinity - every time, place, person and situation is within their gaze and their understanding. Think about it. Pretty hard to get your head around isn't it?!
With the ascended masters on our side as our champions and advisers, the path back to God has been carved a little more firmly and we are in a wonderful position to reach our ascension. As Jesus (the best-known ascended master in the West) said:
He that believeth on me, the works that I do shall he do also; and greater works than these shall he do; because I go unto my Father. (John 14:12)
Our path has been made easier, because of the many who have succeeded before us.
Are ascended masters the same thing as ghosts and departed spirits?
Not at all! When a person passes on at the end of their life, their soul will go to a plane of consciousness that is fitting for the level of spiritual attainment they've reached so far (there are no less than 33 levels of heaven!), where they receive tutoring in preparation for their next embodiment.
Or they might hang around on earth for a while, if they can't figure out how to let go of their attachment to the things of their previous life. Those are the ghosts and departed spirits. They're just souls that have passed on and not gone anywhere, so, however educated they might have been, they don't have any more insight than they did when they were alive.
Learn From The Best
The wisdom that the masters pass on to us, via their messengers through the ages, is priceless and comes directly from the level of what we would generally call 'God' because they have attained union with God through the ascension. Many books have been published on the teachings that these great beings have given mankind, along with audio and video recordings of dictations (messages from the heaven-world conveyed through the Holy Spirit to an anointed messenger).
Along with reading and listening to teachings that the masters have already given us, we can also make contact with them ourselves through decrees, prayer and spiritual meditation. (See the Giving Devotions section for more info on this).
Alongside Jesus Christ, some of the more well-known ascended masters include Gautama Buddha, Mother Mary, Saint Germain (also written as St Germain), and Maitreya.
You can learn about hundreds of ascended masters in the Summit University Press publication The Masters And Their Retreats. It's compiled in a style that's easy to reference with entries for each individual master organized alphabetically by name. It includes details about their past lives, teachings, specializations, and their etheric retreats. A very interesting read to dip in and out of.
For a briefer description of eight of the ascended masters, known as the chohans (lords) of the seven rays of God, have a look at this list provided by The Summit Lighthouse.
The Masters and Their Retreats by Mark L. and Elizabeth Clare Prophet
The lives of the ascended masters, their incredible etheric retreats — temples and cities of light in the heaven world — plus instruction for safe soul travel during sleep, and how to get the most out of your etheric retreat experience.
The most comprehensive guide ever written — 500+ pages of authentic source material with pictures. A "must-have" resource for serious students, and a delight for those just discovering the ascended masters and their teachings.