What is meant by semi shade, sun to shade and shade to sun?

Exactly what is meant by semi shade or sun to shade and shade to sun?
Thank you.

Dear Jerri,
There are many different definitions of sun, part sun, and shade.  Add to that the different light conditions in each individual garden and you have a very confusing situation.  I find it useful to define the conditions as follows and then assess each garden spot from there.

Full Sun:  More that six hours of direct sun per day.  Sites with little or no tree cover and/or western exposures.

Part Sun/ Part Shade:  Direct sun for 4-6 hours per day.  Sites with eastern exposure or those shaded in afternoon by large trees or buildings.

Shade:  Less than 4 hours of sun per day.  Generally considered to be in areas under mature trees or where buildings block sunlight most of the day.

To determine what exposure you have for any site you should observe the site at various times during the day.  Figure out when the site is in shade or sun; determine the number of hours of sunshine and the time of day the sunshine hits your site.  Morning sun for six hours will be acceptable for many sun or part sun plants while four hours of afternoon sun could cause leaf burn and bleaching on part sun or shade loving plants.  Watch your plants for signs their light requirements are not being met.  Long leggy growth is a sign that the plant is not getting enough sun, while red (sun burned) or pale (bleached) leaves might mean too
much sun.

I hope these basic guidelines help clear up the confusion.