There are two types of water hardness: temporary and permanent hardness. Temporary hardness is due to the presence of calcium hydrogen carbonate Ca(HCO3)2(aq) and magnesium hydrogen carbonate Mg(HCO3)2(aq).
'Internet' is the shortened form of 'INTERnational-NETwork' which is the interconnected network of all the Web Servers worldwide. It is often called the 'World Wide Web'.