Stack is one of the core concepts in Spacelift. A stack is an isolated, independent entity and the choice of the word mirrors products like AWS CloudFormation (support coming soon), or Pulumi (which we already support). You can think about a stack as a combination of source code, current state of the managed infrastructure (eg. Terraform state file) and configuration in the form of environment variables and mounted files. Unless you're using Spacelift only to host and test private Terraform modules, your account should probably contain one or more stacks to be of any use. For example:
Here's a few helpful articles about stacks:
In this article, you can learn how to create a new stack;
Here you can see all the settings that are available for the stack;
Here you can learn about stack locking;
Stack states allow users to see at a glance the overall health of their infrastructure, and the level of development activity associated with it.