Researchers at an American university have created a "bug atlas" based on the sites where microbes are most likely to thrive.
The hotspot areas are the palms, index finger, the back of the knee and sole of the foot, the study found, with humans carrying a personalised community of bacteria wherever they go.
The study, which focused on 27 sites of the human body in nine volunteers over three months, also found that different individuals carry unexpectedly wide variations of microbe populations,
The researchers, from the University of Colorado at Boulder, probed numerous niches where bugs were likely to be found, including ear canals, nostrils, the mouth, and the lower intestine.
A total of 18 different skin sites were tested ranging from the forehead and armpits to forearms, palms, fingers, navels, the back of knees and the soles of feet.
Study leader Dr Rob Knight said: "The goal is to find out what is normal for a healthy person which will provide a baseline for further studies to look at people with diseased states. One of the biggest surprises was how much variation there was from person to person in a healthy group of subjects."