Bip148 refers to a significant proposal in the Bitcoin community aimed at addressing a contentious issue related to block size and transaction capacity. It is a user-activated soft fork (UASF) that sought to enable Segregated Witness (SegWit) activation by allowing users to signal their support directly from their nodes.

The motivation behind Bip148 arose from disagreements among developers and miners about how to implement SegWit. While some miners were hesitant to adopt SegWit, Bip148 empowered users by enabling them to enforce the upgrade regardless of miner support. When Bip148 was activated, wallets and nodes that supported the proposal began signaling for SegWit.

If a sufficient percentage of users (more than 95% of nodes) signaled for it, the upgrade would go into effect even if miners did not cooperate. This approach highlighted the importance of users’ roles in the Bitcoin network and aimed to resolve scaling issues. Ultimately, Bip148 played a crucial part in successfully activating SegWit in August 2017, improving transaction efficiency and paving the way for future scalability solutions.