I am little bit confuse on sub domain and sub folder, which is the best choice.
1. My website all ready have page rank 2 .Now I want create some more section in details. Should I go for sub domain or sub folder? Which one is better?
2. My another question is did my present page rank will follow in all my sub domain or I have to promote individually all sub domains and what is case in case of sub folder ?
3. What you thing which is easy to remember sub domain or sub folder from the point of view of visitor?
Thanks in advance.

I'd go for folder, unless the new section can stand as somewhat independent (and you also want to promote it separately), and you want to keep it somewhat separated from your main site.

There should be no difference SEO wise, whichever way you go about it.

I think sub folders are easier to remember from the point of view of your visitors.

I will go for sub folder.
I am not sure that present page rank will follow in all sub domains but I think it will work for sub folders.
Sub folders are easy to remember.

Definitely sub folder

Hello,

Typically a sub-domain is suggested. A sub-folder is only going to assist when the product you be likely to promote is actually significant to your business. In the later case Google & other Search Engines would index it as an individual website. Typically if you have the folder connected to your website, it should continue your traffic & clicks. A website with a good user interface is easier to memorize.

id go for a subfolder because it is easier to remember

I'll go for sub folder....!!

They are equal but "If you’re a newer webmaster or SEO, I’d recommend using subdirectories until you start to feel pretty confident with the architecture of your site."

Look what Matt Cutts say:
http://www.mattcutts.com/blog/subdom...ubdirectories/