Lists are native part of the Python language and this part makes programming easy and speedy. But every Moon has a dark side and I would like to add some light to it. Problem of the list is heavy resource's usage. Everyone should keep in mind this during coding. Simple example from python tutorial: myfile = open("myfile.txt") myfile.readlines() Python opens file and creates a list from each line in it. Simple script below provides some information about executing speed and memory usage: #!/usr/bin/python import datetime import resource currenttime = datetime.datetime.now() print "="*20 print "Creating a file " print "="*20 myfile = open("textfile.txt", "w") simplerange = xrange(10000000) try: for i in simplerange: myfile.write(unicode(datetime.datetime.now())) myfile.write('\n') finally: myfile.close() timespend = datetime.datetime.now()- currenttime print timespend print "=...