I'm trying to create a mobile application that connects to Dynamics crm 365 and I'm really confused about how to start it. I have a lot of questions in my mind like what is Xrm and is there anything else to use instead of it.
Which is better creating mobile app(android, IOS, WindowsPhone) or using phonegap. How to connect to server with xrm?
To connect to XRM:
Enter your Organization's URL here, it should look like: https://"yourOrganizationName".crm4.dynamics.com
Following this, you'll have to use your login credentials, use the same credentials you use to connect to the CRM through the Web Interface.
About App development:
If you search for "SDK Dynamics 365" and open the MSDN site, you should find documentation to help you better understand how XRM works. Server to Server authentication could be a mean to achieve your goal even though Microsoft has provided an API to do just that!
Check out the "Microsoft Dynamics 365 Web API" which should pretty much cover all of your needs in terms of App development as it is based on oDATA.