Wearable activity trackers for tracking, monitoring, displaying, measuring, storing and reminding users to perform hand and bodily hygiene and disinfection, and of body temperature; Wearable activity trackers for developing, increasing and promoting habits of personal sanitation and hygiene, and healthy lifestyle; Wearable and non-wearable activity trackers for data transmission via wireless and wired communications networks; Data recording apparatus; Wearable activity tracker for tracking, g...