Glossary

What is ARI?

ARI stands for Availability, Rates, and Inventory — the three pieces of information your PMS pushes to every OTA via the channel manager. Whenever a hotelier says "is ARI synced?", they mean "do all the OTAs show the right rooms at the right prices?"

The three components

Availability

How many of each room type you have free for a given date. Tonight's availability for "Deluxe King" might be 3 (out of 5 total — two are already booked).

Availability changes constantly: every new booking decrements it, every cancellation increments it, every block (owner blocks for personal use, maintenance, etc.) reduces it.

Rates

What you charge per night for each room type on each date — and often varied by length of stay or guest segment. Your "Deluxe King" might cost $180/night on a Tuesday, $240/night on a Friday, and $400/night on New Year's Eve.

Rates can also be derived: a rate plan might say "Deluxe King non-refundable is the standard rate × 0.85." Or "weekly stays get 10% off." The channel manager pushes the calculated final rate for each date, not the formula.

Inventory

The room types themselves, with their characteristics: name, description, max occupancy, bed configuration, amenities, photos. This changes rarely — usually only when you add a room type or renovate.

"Inventory" sometimes also refers to the count of available rooms (which is technically Availability) — the term gets used both ways in the industry. When in doubt, ask "do you mean room types or room counts?"

Why operators care about ARI sync

Because if ARI doesn't sync, bad things happen:

Overbooking — Two OTAs both show 1 room available; two guests book; you have only 1 room. You have to cancel one guest, the OTA fines you, the guest reviews you 1-star.
Lost revenue — You raise your weekend rate from $180 to $240; the change syncs to Booking.com but lags on Airbnb. Airbnb keeps selling at $180. You lose $60 × every Airbnb booking that came in during the lag.
Manual fixes everywhere — Without automated ARI sync, the alternative is opening each OTA's extranet, updating the calendar manually, hoping you didn't miss one. Hours per week, error-prone.

How fast should ARI sync?

Modern channel managers push ARI updates within seconds. Booking.com and Airbnb accept changes near-instantly; smaller OTAs may take 5–60 seconds. End-to-end: a booking on Booking.com should reduce your Airbnb availability within ~30 seconds.

If your channel manager takes minutes (or worse, hours), you're running on outdated infrastructure. Look for "real-time ARI" or "webhook-driven sync" in vendor descriptions.