The failure to use the care and diligence demanded by the special relationship between the plaintiff and defendant under particular circumstances that arise from inattention, careless conduct, or want of care
The contract is the foundation of the defendant's liability, and the obligation to answer arises from a breach of contract because of the defendant's failure to exercise due care in its performance
A separate source of obligation independent of the contract, where the pre-existing obligation is derived from the general obligation or duty to observe the standards of care set by society in dealing with other persons
Obligations where each party is a debtor and a creditor of the other, and the performance of one is conditioned upon the simultaneous fulfillment of the other
Obligations that arise from the same cause, where each party is a debtor and a creditor of the other, and the obligation of one is dependent upon the obligation of the other