"Also, there is an intuitive notion that most individual stocks or bonds move with the aggregate market. Therefore, if the overall market rose, an individuals portfolio probably also increased in value. To supply investors with a composite report on market performance, some financial publications or investment firms have created and maintain stock-market and bond-market indexes."

1-What they mean by aggregate market? Does it mean macroeconomic phenomena?

2-Dose index values represent the aggregate market? If the index represents the aggregate market, then why each index has different values than others, and how can I know if the index for a portfolio of for stock of for bonds?

I'm confused, plz help me