Your downline shows you how many people you have reached by giving out your Care Badges:-

"If Peter gives a Care Badge to Mandy (level 1), who purchases a Care Card and gives a Care Badge to Jacques (level 2), who purchases a Care Card and gives a Care Badge to Max (level 3), who purchases a Care Card and gives a Care Badge to Betty (level 4), etc, etc, etc.  All these people are in Peter's downline.  Our system displays to 10 levels."