These are sets of stocks that are used for comparisons to get a measure for how things are going with the market or with an individual stock.

Dow Jones Industrial Average (DJIA or just the "Dow") - This is the oldest index started by Charles Dow back in 1896.  It's a set of 30 very large industrial companies like General Electric.  The Dow is not thought to be the best indicator of the entire market since it's only 30 companies and they are all really big...  But, still these companies make up about 25% of the entire value of the New York Stock Exchange (NYSE).

Standard & Poor's 500 Stock Index (or just the "S & P 500") - Since this index is based on the performance of 500 companies, it's considered to be the best gauge of the overall market.

Russell 2000 - This index contains the 1001th to the 3001th largest companies.

Wilshire 5000 - This index contains a wide range of stocks from the New York Stock Exchange, the American Stock Exchange and the NASDAQ.

When you read about mutual funds, you'll find that you can buy packages of stocks that mimic the overall results of the above indexes.  So, when you hear on the news that the S & P 500 is up, you'll be up too!