Is the API two-way or one-way?

Is the API two-way or one-way?

Having been a Zoho CRM user for a few years now, we are finally ready to implement an API integration between Zoho CRM and our internal systems (Oracle, etc.). During a recent kickoff discussion, our IS manager asked if Zoho's API was one-way or two-way. Going through the online API documentation, I really couldn't say if it is or not.

This would be important to us because we will likely want to push some information from our internal systems to Zoho as well as vice-versa. 

An answer is appreciated.

John Galich