Contracts can be classified into various types based on their nature and enforceability. Common classifications include:
1. **Based on Formation:**
- **Express Contract:** Terms are explicitly stated, either orally or in writing.
- **Implied Contract:** Terms are inferred from the parties' conduct or the circumstances.
2. **Based on Enforceability:**
- **Valid Contract:** Meets all legal requirements.
- **Void Contract:** Lacks legal effect from the beginning.
- **Voidable Contract:** One party has the option to enforce or void the contract.
- **Unenforceable Contract:** Valid but cannot be enforced due to legal reasons.
3. **Based on Performance:**
- **Executed Contract:** Fully performed by both parties.
- **Executory Contract:** Not fully performed by one or both parties.
4. **Based on Number of Parties:**
- **Bilateral Contract:** Promise for a promise (two parties involved).
- **Unilateral Contract:** Promise for an act (one party makes a promise, and the other performs an act).
5. **Based on Time:**
- **Periodic Contract:** Repeats at regular intervals.
- **Fixed-term Contract:** Lasts for a specific period.
6. **Based on Nature of Obligation:**
- **Unconditional Contract:** No conditions attached.
- **Conditional Contract:** Depends on the occurrence of a specific event.
Understanding these classifications helps in interpreting and applying contract law appropriately.