Why are there lines with company names in the Hosts file?
They are there so that you may easily tell which firm’s ads you are blocking with each entry. This way, if you want to unblock all of an ad firm’s sites, you may do so by putting a # symbol in front of each of its servers. Having the servers broken into company groups makes it easier for you to determine which servers you wish to block and which ones you don’t, if you want to decide for yourself.