A "light" introduction to the metric system may be found at The Metric System According to milli meter and the metric system itself begins with the definition of meter. Once the meter (for length) is defined, other units based on the meter are define. Grams are used for mass. Liters are used for volume. Next come the prefixes. Prefixes create multiples and parts of the basic units and this makes measusrement of all sorts easier. This page deals with the metric prefixes  a base ten system of naming units. The above mentioned introduction really explains it quite nicely. This page contains a chart of the prefixes and 3 examples.

To examine the world from the very small to the very large in terms of their metric lengths and things relatively the same length, visit "The Scale of the Universe 2" by Cary and Michael Huang. 
Prefix  Symbol  Multiply by 
yotta  Y  10^{24} 
zetta  Z  10^{21} 
exa  E  10^{18} 
peta  P  10^{15} 
tera  T  10^{12} 
giga  G  10^{9} 
mega  M  10^{6} 
hectokilo  hk  10^{5} 
myria  ma  10^{4} 
kilo  k  10^{3} 
hecto  h  10^{2} 
deka  da  10^{1} 
UNIT  1  10^{0} 
deci  d  10^{1} 
centi  c  10^{2} 
milli  m  10^{3} 
decimilli  dm  10^{4} 
centimilli  cm  10^{5} 
micro  µ  10^{6} 
nano  n  10^{9} 
pico  p  10^{12} 
femto  f  10^{15} 
atto  a  10^{18} 
zepto  z  10^{21} 
yocto  y  10^{24} 
10^{3}  10^{2}  10^{1}  10^{0}  10^{1}  10^{2}  10^{3}  
kilo  hecto  deka  UNIT  deci  centi  milli  
k  h  da  1  d  c  m  
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10^{12}  10^{9}  10^{6}  10^{3}  10^{0}  10^{3}  10^{6}  
tera  giga  mega  kilo  unit  milli  micro  
T  G  M  k  1  m  µ  
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