Jack of all trades

 

This common phrase is a shortened version of "jack of all trades and master of none."  It refers to those who claim to be proficient at countless tasks-but cannot perform a single one of them well.

The phrase was first used in England at the start of the Industrial Revolution.  A large number of efficiency experts set up shop in London, advertising themselves as knowledgeable about every type of manufacturing process, trade and business.  

But soon became evident that their knowledge was limited and of no practical value. Suspicious industrialists started calling these, self-appointed experts "jack of all trades and masters of none." These experts, are still with us and so is the phrase.