Summary Fischer Projections and Their Use

They are most useful for compounds with two or more asymmetric carbon atoms. 

The vertical lines project away from the viewer, the horizontal lines toward the viewer. 

The carbon chain is placed along the vertical, with the lUPAC numbering from top to bottom. In most cases, this places the most oxidized end (the carbon with the most bonds to O or halogen) at the top. 

The entire projection can be rotated 180° (but not 90°) in the plane of the paper without changing its stereochemistry. 

Interchanging any two groups on an asymmetric carbon (for example, those on the horizontal line) inverts its stereochemistry. 

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