While it may vary slightly from place to place or from chemical to chemical, esters are chemical compounds that are typically derived from an acid. Typically, esters are going to derive from some type of carboxylic acid and an alcohol. Esters are typically going to be more polar than ethers but less polar than alcohols. Typically, esters are going to fall into the gas category and when it comes to the reactions of the esters, they will react with nucleophiles. It’s also important to note that there really is not just one single ester. There are a variety of different esters so it’s important to know that there are plenty to differentiate.