The index.php script first calls readCounter.py to read the current number of visitors and output that number. The readCounter creates a counter.txt file if the file doesn't exist already. Then index.php takes that number and displays it on the webpage. Then it pass that number as an argument to writeCounter.py. writeCounter.py then increments that number in the counter.txt file for readCounter.txt to read again next time someone visits the site. index.php then records the current date and time the visitor visited in timeVisited.txt to keeps track of when visitors visit the site.