A PMS is an integrated hard and software management system that automates the full multi-user process of making reservations, checking guests in and out, delegating housekeeping tasks, handling of Point of Sales terminals, invoicing, price management, etc.
A channel manager is a software system that helps you managing your property across multiple different distributing channels.
A booking engine is a software system that helps you selling your accommodation on your (own) website. It offers your visitors 24/7 information about availability, the option to make a reservation. It generates, collects and distributes essential data about reservations, like prices, user name, email address and telephone number. It prevents double booking by automatically blocking reserved dates. It exchanges bookings with third parties.
Booka.Place is a booking engine.
A booking engine handles bookings, it shows available accommodations and/or dates, it calculates the right price for the selected date range and choosen options, it registrates the required data, updates your calendar and handles the confirmations etc. It can also handle the direct (credit card) payment of the booking.
Nowadays most visitors prefer direct booking above starting a mail conversation about all the required details with the risk of loosing the desired accommodation in the meantime.
The owner of the website can decide if a booking is legally binding or has to be confirmed first.