Which version of the IEEE 802.11 specification was the first widely accepted wireless standard branded as Wi-Fi?

The designation of the first widely accepted wireless standard branded as Wi-Fi goes to IEEE 802.11b. This standard, ratified in 1999, significantly advanced wireless networking by enabling data rates of up to 11 Mbps in the 2.4 GHz frequency band. Its compatibility with older 802.11 specifications and the widespread adoption of this standard led to the proliferation of Wi-Fi technology in homes and businesses.

The success of 802.11b can be attributed to its balance of performance, range, and ease of implementation, which made it attractive for various applications, ultimately leading to the mass adoption of wireless networking. While other standards, such as IEEE 802.11a, were introduced at the same time, they did not achieve similar levels of acceptance and deployment, largely due to their use of the 5 GHz band, which resulted in shorter ranges and incompatibility with many existing devices at that time.