This will help your new post to appear in search engine as fast as possible.
When ever you publish, edit or modify a post, WordPress sends ping to all the Ping services which is listed under your ping update service. So this way, ping services get notified about new post and search engine will quickly index them.
Now by default WordPress notifies all major ping services but we can always extend our limit by pinging more services by adding them manually.
Over the time, I have compiled a list of ping services for WordPress, which will help you to ping more services. Here is list of my working WordPress ping list.
How to add or update WordPress ping list:
Login to your WordPress dashboard. Go to Writing under settings tab and scroll down to update services and add all the above ping list. Here is a screenshot for quick understanding: