Am new to SAP.I would like to know about the SAP certification(TBIT).

Am new to SAP.Am into a project were i work on SAP PI.I would like to know about the SAP certification(TBIT).But everything is so confusing...are there any different levels for this exam...some wer i read there are 2 types 1.Associate certification 2.Professional certification in another site i read there are 2types of exam 1. Development Associate 2. Technology Associate so what does that mean? PLEASE give me EVERY POSSIBLE bit of INFORMATION about SAP PI certification and also the books i can refer for the exam.am at acratch level..so even the smallest possible info is very important to me