Escape From Tarkov's closed alpha kicked off last year, but you could only access it by buying an edition of the game that was higher than standard. This means you'd have to shell out at least $75 USD for the Left Behind edition to get inthe standard edition costs $45 USD. However, with the launch of the closed beta, you can get in no matter which edition you bought: as long as you preorder the game, you're in.
Closed beta invitations will be distributed in waves, so if you haven't received yours yet, then you should be getting one soon. Developer Battlestate Games has said on its website that "within a week, every package owner shall receive an invitation email."
As for what's in the closed beta, Battlestate has listed off a handful of some of the more "significant" changes, which you can see below.
The first part of the largest game locationShoreline
Reworked the balance of existing locations, in addition to new spots to explore
More useful items, medicines, and equipment
Advanced arsenal of weapons and weapon modifications
Balanced the economy and insurance system
Added general chat to search for info or raid companions
"In recent months, we have done a formidable job optimizing the speed and stability of the game, fixed a lot of errors," Battlestate head Nikita Buyanov said. "Our main task is to make it comfortable to play for everyone. Therefore, I hope that players will understand the precautions we took with the gradual admission. Of course, the development of the game doesn't stop here. It will grow richer with features and content with every consecutive update, as soon as they are ready. For example, the closed beta testing will be soon expanded with the quest system."