Even though the three basic sun exposures are full sun, part sun and shade, the last one comes in so many variations, all with their own little quirks, that it deserves a full chapter all to itself.
Full sun exposure means eight hours or more of direct sunlight a day, without any large elements casting shade at any point. Full sun exposure is the beloved of all annuals, vegetables, roses and a good chunk of herbaceous perennials. With very few exceptions, given a chance, a plant will do better in the sunlight. No plant designated for full sun exposure will thrive in any type of shade or part shade. Don’t waste your efforts planting them there.
Part shade gets four to six hours of direct sunlight a day, and the shade is usually dappled through the foliage of a high tree canopy. Part shade plants will do just fine in full sunlight, but they tolerate slightly lower levels of sunshine. The closer you get to the four hour range, the less the plants will bloom.
Shade is complicated. There are six basic types of shade, and you can find more information about them in this article, but the main characteristic of it is that every shade loving plant thrives in a very specific type of shade. Dry shade is the most difficult to tackle; if anything else fails, try an evergreen ground cover, like ivy, pachisandra or vinca.
Sun exposure changes throughout the year, and what is a part sun garden in spring will turn into a woodland shade garden in summer. Take some time to observe the sun path as it relates to your garden and plan the plantings accordingly.

Author's Bio: 

Main Areas: Garden Writing; Sustainable Gardening; Homegrown Harvest
Published Books: “Terra Two”; “Generations”; "Letters to Lelia"; "Fair"; "The Plant - A Steampunk Story"
Career Focus: Author; Consummate Gardener;
Affiliation: All Year Garden; The Weekly Gardener; Francis Rosenfeld's Blog

I started learning about gardening from my grandfather, at the age of four. Despite his forty years' experience as a natural sciences teacher, mine wasn't a structured instruction, I just followed him around, constantly asking questions, and he built up on the concepts with each answer.

I started blogging in 2010 to honor his memory and share the joy of growing all things green and the beauty of the garden through the seasons. Two garden blogs were born this way: allyeargarden.com and theweeklygardener.com, a periodical that followed it one year later. I wanted to assemble an informal compendium of the things I learned from him, wonderful books, educational websites, and my own experience, in the hope that other people might find it useful it in their own gardening practice.