Semi-sun/semi-shade?

Sun, semi sun/ semi-shade and shade plants What does this mean exactly? 

Often we see a label on the plant with information whether the plant needs sun, semi sun, partial shade or shade. But what does this mean exactly? 

Sunplants need approximately 5 hours per day at the hottest part of the day. 
Semi- sun/ semi-shade means that the plant can be about 4 hours a day in the sun  and then prefer to stand in the (semi) shade. 
Shade Plants prefer to stand approximately 2 hours in (full) sunshine a day and prefer to stand the rest of the day in the shade. 

When a plant can stand in the sun or shade, it has no specific requirements regarding sunlight and can grow well in sun or shade (and blossom). 
A plant that likes light shade, prefers a bright spot position, without getting directly into the bright sun (reflected light). 
Plants which like filtered sun, prefer to stand under a tree, so that they do not come into direct contact with the sunlight. 

How do you determine where the most sun is in your garden? The easiest way to do this is through Google maps. Look at where the north is in relation to your house. If you've determined where north is then you automatically know where the east, south and west is and you know where the sun rises, when it is at his highest state and where the sun sets. This is the way to check where you get the most hours of sun in the garden. Of course you also observe on a bright summer day where the sun-spots and shade-spots are in your garden.