LTI provides a framework through which an LMS (Canvas) can send some verifiable information about a user to a third party. For LTI to work, the third party needs to provide a consumer key and shared secret that Canvas can use to generate a signature to verify the authenticity of the data sent. By default most user information is anonymized, but this can be changed when the configuration is first set up.
From Canvas Basics Guide > What are External Apps (LTI Tools)?
LTI tools must be approved for use under NUS Cloud Policy.