It depends on if your question is why it is free to use or if it is free to submit content.
It is free to use because of that a high amount of the Internets traffic does not like to pay money for services such as finding internet content, this will highly increase user amount. Google sells ads to maintain their business.
It's free with a Google account. Google accounts are also free.
Google calendar is actually free to use for individuals. It is accessible from your Google homepage and can be a useful addition to a physical diary.
Yes. Google calendar is free to use.
Skype is similar to Google Voice and there is a free app.
No, it is free to use!
The Google Earth plugin is free. It can be downloaded with the free version of Google Earth (they're bundled together) or by itself from Google's website (see link below).UPDATE: Google Earth Plugin has been deprecated as of December 12th, 2014.
If you have a google account, you can download the free google app It has google docs.
You can visit the Google app store to know that. Google apps that are free do not charge money for them.
You can download the free version of Google Earth at the site in related links.
Yes it is free
Its to show the brand google... Google wants you to use their services and if they are free more people will use them. Its for adverting and to show the brand name "Google".
Yes, but you have to sign up for a Google Account, which is also COMPLETELY FREE!