Conclusion

A mutual fund brings together a group of people and invests their money in stocks, bonds, and other securities.
The advantages of mutuals are professional management, diversification, economies of scale, simplicity and liquidity.
The disadvantages of mutuals are high costs, over-diversification, possible tax consequences, and the inability of management to guarantee a superior return.
There are many, many types of mutual funds. You can classify funds based on asset class, investing strategy, region, etc.
Mutual funds have lots of costs.
Costs can be broken down into ongoing fees (represented by the expense ratio) and transaction fees (loads).
The biggest problems with mutual funds are their costs and fees.
Mutual funds are easy to buy and sell. You can either buy them directly from the fund company or through a third party.
Mutual fund ads can be very deceiving.