Check out this talk about Pact and the slides below from one of the Pact authors for an introduction.
For a great explanation of consumer-driven contracts (and Pact!), check out this talk from Atlassian at their 2016 summit: Verifying Microservice Integrations with Contract Testing.
Hear how Soundcloud "Move Fast and Consumer-Driven-Contract-Testing Things" in their talk from MicroXchg 2017.
You can get help on Pact from the following channels: