The document describes 6 levels of IoT systems with increasing complexity. Level 1 has a single device that performs all functions. Level 2 has local analysis and cloud storage. Level 3 has cloud storage, analysis and applications. Level 4 has multiple analyzing nodes. Level 5 uses a coordinator node. Level 6 has independent nodes that communicate with the cloud. Each level is illustrated with an example system like home automation, smart irrigation or weather monitoring. The document also lists some common IoT issues as security, privacy, interoperability, legal compliance, and economic challenges.