What are the differences between investing in a 401k and investing in index funds?

Investing in a 401k involves contributing a portion of your salary to a retirement account offered by your employer, often with matching contributions. This money is then invested in various options, including index funds, which are a type of investment that tracks a specific market index. Investing in index funds outside of a 401k allows for more control and flexibility in choosing specific funds, while a 401k offers tax advantages and employer contributions.