Triathlon series usually score each race in one of two ways. Place points give a set number of points by finishing place in each age group. Time-based points score each athlete as a percentage of the winner’s time: the winner gets 1,000, and someone who took 10% longer gets about 909. Time-based scoring rewards racing hard to the line even when the podium is out of reach.
Standings are almost always kept by age group and gender, and most series count a best few races so missing one is not fatal.