Step 1: Understanding the Concept:
Communication in an organization can be formal (through official channels) or informal (through social interactions). This question focuses on how information travels when it is not officially released.
Step 2: Detailed Explanation:
When employees obtain information by "overhearing" rather than through an official memo or meeting, they are engaging in informal communication.
The rapid, unstructured spread of such information, which often carries rumors or speculations like "layoffs," is specifically known as the Grapevine.
While the Grapevine is very fast, it is often inaccurate because the information is not verified by the management.
Step 3: Final Answer:
The type of communication indicated is Informal Communication (Grapevine).