Front-running is a form of market manipulation where a trader uses non-public information or access to upcoming trades to trade ahead of others, gaining an unfair advantage. This can include:

1. _Trading ahead of large orders_: Executing trades before a large order is filled, affecting market prices.

2. _Using confidential information_: Trading on non-public information about a company or market conditions.

3. _Early access to orders_: Trading on orders before they are publicly available.

4. _Abusing privileged information_: Using information from a position of trust, such as an investment bank or brokerage firm.

Front-running is illegal and can lead to:

1. _Fines and penalties_: Regulatory fines and legal penalties.

2. _Reputation damage_: Loss of credibility and reputation in the market.

3. _Legal action_: Criminal prosecution for fraud or market manipulation.

4. _Industry bans_: Suspension or revocation of trading licenses or memberships.

To prevent front-running, markets and regulators implement measures such as:

1. _Insider trading laws_: Prohibiting trading on non-public information.

2. _Trade surveillance_: Monitoring trading activity for suspicious patterns.

3. _Access controls_: Limiting access to sensitive information and trades.

4. _Disclosure requirements_: Requiring traders to disclose positions and trades.

5. _Regulatory oversight_: Regular monitoring and enforcement by regulatory bodies.