This week's book giveaway is in the OCAJP forum. We're giving away four copies of Programmer's Guide to Java SE 8 Oracle Certified Associate (OCA) and have Khalid A Mughal & Rolf W Rasmussen on-line! See this thread for details.
You can think of portlets as mini application windows existing cohesively on a page.
One real life example of a portlet is iGoogle which allows you to customize your page with "widgets" These widgets are the portlets