portals in CRM

hi guys..

its me again....

i m 3 yr experienced in abap and nw goin CRM with abap. In fact i have just started. However though i came across peope centric user interface and portals..Now i m in serious doubts and want to knw few very basic things..

1) Is it compulsion to have enterprise portal knwledge for mySAP CRM??

2) wat exactly is the role of portal???

3) IF portals is compulsion , wat level of knwledge i need to have??

if possible can u send me sum docs and cookbooks needed for a starter at gaumzy.abap@yahoo.com//

thanks in advance...

gaurav