Saturatedf fatty acids have single bonds between the carbon atoms of the aliphatic chain, and each carbon therefore holds the maximum possible number of hydrogens. Unsaturated fatty acids hae one or more double bonds and less than maximal hydrogen atoms. Triglycerides are produced when three fatty acids are joined to a single glycerol molecule through dehydration synthesis. They are neutral, since the acidic ends of the original fatty acids have been used in the bonds, and there are no charged or polarized regions remaining. Triglycerides are hydrophobic.
Triglycerides built of saturated fatty acids are fats and have a high melting point.
They tend to be solid at room temperature. Fats are typically produced by animals. Oils are built from unsaturated fats. Polyunsaturated fats are oils with many double bonds in their fatty acid chains. Oils have lower melting points than fats, and are liquid at room temperature.