Bluetooth Mesh allows devices to communicate with one another via intermediate Bluetooth devices thus removing the limitations of the point to point communication range. It works using standard scanning, advertising and optional GATT connection. The mesh has Models that describe standard interactions such as On/Off used in lighting. New models can be created for custom usecases.

Introducing Bluetooth Mesh Networking
Bluetooth mesh networking FAQs
Bluetooth Mesh Overview
Mesh Specifications
Bluetooth Mesh Technology Overview

Bluetooth Mesh Battery Use
Take the Fast Track to Bluetooth 5 Mesh Networking
Bluetooth Mesh Proxy Kit Available
What is a Bluetooth mesh network?
Mouser ezine – Understanding Bluetooth 5 and Mesh
The highlights of Bluetooth mesh networking technology
Bluetooth SIG Mesh Rationale
The Bluetooth Mesh Standard: An Overview and Experimental Evaluation
Bluetooth Mesh and Battery Use
Bluetooth Mesh Networking Learning Center
Bluetooth Mesh Design and Implementation
In one year, Bluetooth Mesh surpasses all expectations
Nordic Beacons and the Bluetooth SIG Mesh
Beacons and the Bluetooth Mesh
BLE Mesh Introduction
Bluetooth Mesh Throughput
An introduction to Bluetooth mesh for Android developers
Designing Bluetooth Low Energy Smart Applications with Bluetooth Mesh
The Bluetooth Mesh Standard: An Overview and Experimental Evaluation
How to Deploy BlueZ v5.50 on Raspberry Pi 3 and Use It