The singer, along with her bandmates Victoria Beckham, Mel B, Emma Bunton and Mel C, took the world by storm when they burst into the music scene in 1996 and she believes the reason they were so successful is because everybody could relate to them.
Speaking about the forthcoming West End play, 'Viva Forever!', which is based on their songs, Geri said: ''The show is about bringing the Spice legacy to a new generation. Spice Girls is about unifying the world - every age, every gender, everyone. It's woman power, it's an essence, a tribe.''
Mel B added that the show ''reminds you that your best girlfriend - you want to be there for her more than anybody else''.
Despite fallings out between band members in the past, Geri insists the girls are likes sisters, as they love each other but also argue.
She told The Sunday Times Magazine: ''It's like a family. Families are never perfect, but there's always that foundation of love.''