Spirit guides are real, or  a better way to explain is, some have lived before and some have chose not to live in a physical life. 
A guide won't judge you, tell you what to do or fall out with you as they have evolved spiritually to a higher frequency, they hold none of the traits of the physical life such as any negative feelings. Some will have lived before as friends and family also people you will have known will also help you, giving you guidance for your best outcome in your life, its your choice to follow it or not. Some guides you won't have known, as these will be the ones who chose to be guides once they passed over, but they will resonate with you. 
Their purpose is for guidance and healing in your own life firstly, for those that do open to spirit then your guides will teach and work with you for others.
A lot of people have had imaginary friends when they were children, these would have been guides, as guides are energy, they would have appeared as other children or something that child would have related too, as we are human, our brains need to make sense of things, so they would "fit" to our understanding of the world and surroundings at that time. As our awareness of our world and surroundings grow, so our guides appear to "change".
They guide you from within for your healing, how many times have you noticed old memories that have emotionally hurt or scarred you, start to come to the front of your mind? and you've no idea why?...It's usually because you are going through a similar situation which would cause the same emotional wounds or behaviours, which would again, be stored within. So they help bring memories back for you to release and the choice to change reactions or behaviours which have become a vicious circle for you. This could be situations, people or choices in your life.

Guides will give you feelings and they're usually quite subtle as you begin to trust your "gut" which is the clairsentience, the sensing. As your trust comes, you'll notice pictures appear and you might start to hear too. This can be "foresight for yourself, which comes in with the guidance and healing for yourself too.

Guides and mediumship development
Meditation is the ideal way to connect to your guides, you'll sense them, see them (not always straight away) and you can talk to them. Connecting through meditation helps to build your trust and confidence up as you'll be receiving guidance for yourself.
In mediumship and psychic development, your guides again work with you to open all your senses as there are quite a few, and the more senses you open and become aware of can make a difference to connections and symbols. 
In development there are various exercises that strengthen your blend, as you lift your vibration, spirit lower theirs to make that blend possible as they learn to work with you and your awareness. These exercises would be done in a development class or on a 1 to 1 basis and make a difference to your understanding. 
For more info on workshops and development contact me via email - kerkypa@hotmail.co.uk 

This is very much misunderstood, NO we don't, they're more alive than we are, it's the physical body that expires but the soul is eternal.
In case you didn't know it, they're are around you more than you realise and it's love that brings them closer.
They come back because they want to, and a medium can't force them, some don't come back at all if they don't want to. They come with love and concern for their family, for support and help with grief.
​They ultimately choose to come back