The Stages, also known as: the Houses

The stage or House is the area of focus in which your planets interact with one another and with you.
They can be seen as developmental stages starting with birth in the first stage all the way to transcendental union beyond the body in the 12th stage. 
Here are some of the key words for each of the 12 stages.

First:  You and your body. Your sense of yourself, your birth, your self image.
Second:  Resources available to you in its many forms: financial, emotional, spiritual, etc.
Third:  Communication and siblings, your means of communication as well as your siblings or how you relate to them.
Fourth:  Your roots, home, mother or father. This stage shows your relationship with one of your parents and what home or your roots are about for you. This is who you are when you are behind closed doors at home.
Fifth:  Self-Expression, sex, children. This shows how you express yourself as an individual and sexually. Also indicates how you connect to your own and other people’s children.
Sixth:  How you are of service, illnesses. This stage gives you insight into how you are likely to be of service and can also indicate how illness will be viewed and/or handled.
Seventh:  The other: relationships and partnerships. This stage gives insight into how the other appears to you and how you are likely to be in relationship with others.
Eighth:  Resources of others, death. This stage indicates how you work with other people’s resources such as inheritance or working with other people’s assets.
Ninth:  How you expand your horizons. This area indicates foreign travel, higher education and thought processes, larger philosophies.
Tenth:  Career and social role, mother or father. This stage indicates your relationship with the other parent (usually different from the one in the fourth stage) as well as career path or social role.
Eleventh:  Friendship and communities. This area indicates how you are with larger groups or and with communities such as church, spiritual community, hobby or self interest group affiliations.
Twelfth:  What is behind the scenes, seclusion. This can be the area where you are locked away as in prison, ecclesiastical order (monk, priest, nun), or simply how you may seclude yourself from people or society.

Circle of zodiacEach of these stages holds the entire cast of actors in all of the costumes with all of their tools.
The stages change through time thereby receiving visitors or guests through transits.
Transits are used with the natal chart to show where the planets are at different times in your life and how their relationships with one another change (because they move) over or through time, sometimes highlighting different stages and constellations of planets in an effort to get you to pay attention.
As you can understand, some guests are more welcome than others, especially when they wear certain costumes, use certain tools and act on certain stages. There is a myriad of different combinations available.
Now that you have an understanding of the actors, costumes and stages you are ready to have your chart read.