Jack of all trades

[Jessica]

The other definitions are wrong.
A Jack of all Trades is someone who is decent at everything, but not especially adept at any one thing.

[Britney]

A person who is skilled at a variety of different things, but not to the same level as a person who is specialised in one of these things.

[Little_Girl]

A Jack of All Trades is a master at none, but often better than a master of one.

[Mark Zuckerberg]

A term used to describe someone who knows a lot about many things, but, with the second tag master of none added it transforms into a derogatory phrase meant to emphasize how mastery of one skill is important for deeper knowledge.
However, one, oft forgotten tag is the third one: is oftentimes better than a master of one. Instantly, the term reverses meaning, symbolizing how a person who knows a lot about many things that integrates their skills allows them to surpass even a master of one.
Interesting phrase, nonetheless.

[Becky]

Something that school aspires to develop its students into, a jack of all trades is a well-rounded person who has adapted many skills and is somewhat knowledgeable on many topics but is not an expert (or even an apprentice) in most or even all of the said skills.

[Britney]

Someone who is well read or performs well in a large variety of subjects that is admirable and worth mentioning; but on the other hand doesnt know everything about one thing in particular.