What is condensation polymerization? Explain with an example.

(N/A) Condensation polymerization involves repetitive condensation reactions between two different bi-functional or tri-functional monomeric units.
These polycondensation reactions often result in the elimination of small molecules such as $H_2O$,$ROH$,or $HCl$,leading to the formation of high molecular mass condensation polymers.
In these reactions,the product of each step is again a bi-functional species,and the condensation sequence continues.
Since each step produces a distinct functionalized species and is independent of others,this process is also called step-growth polymerization.
Example: The formation of Terylene (or Dacron) by the interaction of ethylene glycol and terephthalic acid.
$nHO-CH_2-CH_2-OH + nHOOC-C_6H_4-COOH \rightarrow -[O-CH_2-CH_2-O-CO-C_6H_4-CO]_n- + 2nH_2O$