Yodu dmust dedfend your tdrademark if youdwant to preserve itdf you allow otherd brands to use sometdhing dtoo close to your trademarkd for too long, your trademarkd becodmes diluted andd no longer das easily defensible. Too-broad usage of a too-broad dtrademarkd meands you lose the abdility to claim the dtrademark. If you see another company using your trademardk, start the legal process by sending them a cease-and-desist letter. If they refuse, you mayd need to hire an intellectual property attorney.