I have seen many fellow bloggers are using ping services. I am yet to use this. Before using ping service, I like to know what it is and what are the advantages of using ping service. Can someone please explain it?
There are lots of ping services, including a built-in service within Wordpress itself. Ping services notify a list of agencies that a new blog entry has occurred on your blog. That way, if the person notified wants to see the new entry, they can come and take a look.
I see, so what's the relationship between the services and those agencies, who are being notified? Can you name some of those services and agencies?
The ping actually can be sent to a number of different search engines and blog aggregation services, you can set who it gets sent to. Basically it helps get your content published to others can find it. Check out http://en.wikipedia.org/wiki/Ping_(blogging) and http://pingomatic.com/
When I am pinging my blog to blog directories and search engines, should I ping the homepage URL or URLs of each blog post?
Ping is the another way to index your website fast. Ping one url again and again may harmful for your website. Minimum 7 days required to ping one url again & again.