Matter is a new compatibility standard, which most of the big home automation players are involved with, although maybe only for some models.
Amazon basically brought everybody together and said you’re driving our customers crazy, because they don’t know if the products they see in the online store will work with what they already have.
So Google, Apple, Samsung, and Philips Hue, and a bunch of other companies, including IKEA and home, assistant, agreed that they would come up with a new standard for IP address-based devices (which right now and practice means Wi-Fi or thread) so that any device that was matter-compatible could work with any of the major voice assistants. Apple contributed the bridging and Wi-Fi security architecture, Zigbee contributed a bunch of other messaging architecture, and amazingly, three years later, there’s an actual standard and devices are starting to be certified.
The biggest advantage will be that you’ll be able to use more inexpensive Wi-Fi devices with more platforms without having to figure out each time how to make the integration work.
How important that will be varies: people with stronger technical backgrounds, may not need it. It’s more about the mass market consumer who right now can’t figure out whether the sensor they are looking at will work with the Wi-Fi switch They are looking at.
Consumer reports has a particularly good FAQ:
SmartThings is going to support matter, but only one way in: you will be able to add matter compatible devices to your smartthings account, but you will not be able to add your smartthings hub to, for example, Apple HomeKit. Which is disappointing, but there it is.
Here’s the discussion thread in this forum:
Matter - smart home connectivity standard (formerly Project CHIP)