1. Representational State Transfer (REST) is an architectural style that defines a set of good practices, standards, and properties that can be implemented on top of Hypertext Transfer Protocol (HTTP). A web service that conforms to REST standards enables easy interoperability between devices on the internet.
2. MongoDB is a free and open source document store that stores data in a schema-less JSON format, which is highly flexible, and each individual document can have different fields. MongoDB allows ad-hoc querying, indexing, and aggregation out of the box.
3. Kotlin is a programming language for the JVM that has concise syntax, is interoperable, safe, and tool friendly.
4. The data keyword in Kotlin can be used to mark classes whose sole purpose is to hold and transfer data. Classes with this keyword will get the equals(), hashCode(), toString(), copy() functions autogenerated by the compiler.
5. Basic Authentication is HTTP header-based authentication where a header named Authorization is used with the "Basic "+base64Encode(username:password) value to authenticate and authorize users.

6. Integration Testing is an end-to-end functionality testing of an application to verify whether all components are functioning together correctly.
7. Postman is a GUI-based tool to invoke and test RESTful APIs.