This includes basic theory on contracts included on the subject Law on Obligation and Contracts. The sources used are Law on Obligation (12th edition) by Henry de Leon and tiny bit of RFBT (2022) by Soriano, Laco and Mariano to check some concepts. I also include some mnemonics put in here https://www.studocu.com/ph/document/polytechnic-university-of-the-philippines/obligations-and-contracts/law-notes-law-on-obligations-and-contracts-summary/7704734?utm_campaign=shared-document&utm_source=studocu-document&utm_medium=social_sharing&utm_content=law-notes-law-on-obligations-and-contracts-summary