Modern data centers rely on high-speed optical links, and 100G optical transceiver modules (especially the QSFP28 form factor) are now foundational for this connectivity. 100G transceivers convert electrical signals to laser light over fiber, enabling top-of-rack switches to. Building a 25G/100G data center requires a large number of 100G optical modules, which account for a high proportion of the network construction cost. What are the 100G optical module standards and how should we choose? Today, we will briefly sort out the 100G optical module standards and packaging. Upgrade to 100G or 400G optics and save. It features low power consumption, high port density, compact size, and cost efficiency. This article reviews QSFP28 module types and key WDM technologies like CWDM and DWDM.