Most often used as part of filenames in File-Sharing programs
Often linked to spam, but occasionally actually child pornography and sex acts (also known as kiddie porn,) which are, of course, illegal in most countries and also considered evil, immoral and perverted by most of Society as a whole
Thankfully, most hardcare child pornography is actually very difficult to find by the common internet or file sharing user as it uses codenames created by paedophiles to share with their files with one another
Abbreviation used (mainly) in science fiction when describing the process of terraforming a planet i.e. making a planet more "earth-like", improving its chances of supporting Life.
Humidity refers to atmoshperic density, not concetration of vapor (H2O) gas.