Collateral:
Collateral is a security or pledge that is provided by a borrower to a lender to secure a loan. It acts as a form of protection for the lender in case the borrower defaults on the loan. The lender has the right to seize and sell the collateral to recover the amount owed.

Types of Collateral:
There are various types of collateral that can be used to secure a loan, including:

1. Real Estate: Property such as land, buildings, or homes can be used as collateral for a loan. If the borrower fails to repay the loan, the lender can foreclose on the property.

2. Vehicles: Automobiles, motorcycles, boats, or other vehicles can be used as collateral for a loan. If the borrower defaults, the lender can repossess the vehicle.

3. Financial Assets: Investments such as stocks, bonds, or mutual funds can be used as collateral. If the borrower defaults, the lender can liquidate these assets to recover the loan amount.

4. Cash or Savings: A borrower can use cash or savings accounts as collateral. This is commonly seen in secured personal loans or lines of credit.

5. Equipment or Inventory: Businesses may use their equipment or inventory as collateral for loans. If the business fails to repay the loan, the lender can seize and sell these assets.

Advantages of Collateral:
- Lower Interest Rates: Lenders are more willing to offer lower interest rates on secured loans because the collateral mitigates the risk.
- Higher Loan Amounts: Collateral allows borrowers to access larger loan amounts since the lender has a form of security.
- Easier Approval: Collateral provides reassurance to lenders, making loan approval more likely, even for borrowers with poor credit history.

Disadvantages of Collateral:
- Risk of Losing Assets: If the borrower defaults on the loan, the lender has the right to seize and sell the collateral. This can result in the loss of valuable assets.
- Limited Options: Not all types of collateral are accepted by lenders. Some lenders may have specific requirements for the type and value of collateral.

In the context of the question, collateral is the correct answer as it refers to the security or pledge provided against a loan. Tokens coins, promissory notes, and currency are not typically used as collateral, though promissory notes may be used as evidence of debt.