BFF stands for “Best Friends Forever,” describing someone who is your closest, most trusted friend. When you call someone your BFF, you're saying they're the person you share secrets with, laugh hardest with, and count on when things get tough: your most important friendship.

The term became popular in the 1990s and spread quickly because it captured something kids already felt: some friendships feel special and permanent. Your BFF is the friend who knows your favorite songs, understands your jokes without explanation, and sticks by you even when you mess up.

While “forever” sounds absolute, real friendships do change as people grow and move through different stages of life. Sometimes childhood BFFs stay close for decades, meeting up as adults and picking up right where they left off. Other times, people drift apart as their interests change or they move to different places. What makes someone a BFF isn't a promise that nothing will ever change, but the depth of connection you feel right now.

The abbreviation gets used playfully too. You might sign a note to your best friend with “BFF” or create matching “BFF” bracelets. Some kids joke about having multiple BFFs or use “BFFL” (Best Friends For Life) as a variation.