homologue vs orthologue?

[Mark Fry]

Can somebody please tell me the difference between homologous genes,
orthologous genes and paralogous genes.

Thanks

Mark Fry                                          
rm 4330 BMS
Faculty of Medicine                                        
Memorial University of NFLD            
NFLD, Canada             
A1B 3V6                                          
wmfry at plato.ucs.mun.ca                             

An idealist is one who, on noticing that a rose smells better
than a cabbage, concludes that it will also make better soup. 

H.L. Mencken (1880-1956)