Login/ˈlɔːɡɪn/ Definition 1 of 2Pro Tip 1/3Privacy Matters Keep login details private to protect your data from unauthorized access. Never share your login with anyone. Pro Tip 2/3Unique Identifier Your login is often your email or username; it identifies you on a service. Use a memorable login that you don't use elsewhere. Pro Tip 3/3Not Just English Login information can be in different languages or characters, depending on the service. His login for the Japanese game was in kanji.