What does L4L mean?

L4L is a popular hashtag on Instagram that stands for Like 4 Like, or Like for Like. Users use the tag, which has been tagged on around 60 million photos, on their photos in hopes of people liking their photos to exchange likes. Users may comment L4L on another users photos to see if the user wants to exchange likes for likes. This is similar to F4F, or follow for follow, which is popular on Instagram, Twitter, Tumblr, and other sites.

#L4L = Like 4 Like (Like for Like)