PDF stands for Portable Document Format and it was created by Adobe to ease document exchange. Now a days we see Pdfs everywhere - ebooks, printable application forms, cartoon strips, e-magazines etc.. It has become universal format on E-world to provide information has to be read . 
 

Pdfs are created by Adobe Pagemaker which is a bulky software in addition is not a freeware. So generally sometimes we limit ourselfs to send them as word documents. Now there are many useful softwares and easy softwares for creating pdf and doPDF is one of the coolest.