A stock market, equity market or share market is the aggregation of buyers and sellers (a loose network of economic transactions, not a physical facility or discrete entity) of stocks (also called shares), which represent ownership claims on businesses; these may include securities listed on a public stock exchange as well as those only traded ...
Redundancy is a system design in which a component is duplicated so if it fails there will be a backup. Redundancy has a negative connotation when the duplication is unnecessary or is simply the result of poor planning.
Basically, the word redundant can have many meanings. However, it seems to all correlate to being somewhat useless. Example:If you have to do something a considerable amount of times, but doesn't really have any effect(can be repetitive), or could be removed it is redundant. A more common example: If you play video games, mainly Massively Multiplayer Online.