ICS
The "ICS" file contains information related to calendars.
OTA
The abbreviation "OTA" means Online Travel Agency, i.e. accommodation rental agents.
- Airbnb.com,
- Agoda.com,
- Booking.com,
- Tripadvisor.com,
- Wimdu.com.
iCal
This is a calendar data exchange format.
URL
The abbreviation "URL" means Uniform Resource Locator, i.e. a file's internet address.