Money market funds (MMFs) are a low-risk, high-liquidity investment staple, often used as a "cash-plus" strategy to park money while earning more interest than a standard savings account.
You can usually access your cash within 1–2 business days.
The price doesn't go up like a stock; you only earn the interest. Common Types of Funds What are money market funds? | BlackRock
Unlike bank accounts, these aren't government-guaranteed; you could lose money, though it's rare.