LTI stands for Learning Tools Interoperability. It is the industry standard for learning management systems like Blackboard, Canvas and Sakai.
The Courses App in FOLIO will need to meet LTI standards to work with those systems.
Basic information about LTI is here: https://www.imsglobal.org/activity/learning-tools-interoperability
The LTI core spec is here: https://www.imsglobal.org/spec/lti/v1p3/
There is also LTI Advantage. LTI Advantage is Core LTI 1.3 that uses at least one of three services: Deep Linking, Names and Role Provisioning Services, or Assignment and Grade Services.
The only one of those services that could make sense for support in FOLIO is Deep Linking.
Deep Linking specs are here: https://www.imsglobal.org/spec/lti-dl/v2p0
One of the things that we would need to decide collectively is whether LTI Advantage is something we should target above and beyond the LTI Core spec.