Contracts and contract law are at the heart of business  law and commercial law.  Thus, one of the most important  common law claims is for breach of contract.  Under New  York law, the elements such a claim are 1) the formation  of a contract, 2) its breach and 3) damages resulting  from the breach.  Each element raises complicated  questions of law and fact.

First, what is a contract?  A contact is simply an  agreement supported by consideration-- i.e., where each  party has given up something of value.  For example, in  a contract of sale, the seller agrees to sell the goods  and the buyer agrees to pay for them.  Thus, contract  and agreement are used by lawyers interchangeably.

Sometimes, the law suit may be over the meaning of the  contract's terms. The most common terms may be  ambiguous.  For example, the parties may disagree over  the definition of "of" as used in the agreement, just as  Bill Clinton famously said, It depends on what the  meaning of the words 'is' is.

What is a breach of contract?  A breach is simply a  failure by one side or the other to perform its  obligations.  Often there is a question of whether the  breach is sufficient significant to give rise to a  breach of contract claim.  Other times, the question is  whether a breach is excused because the other side  breached first.

What damages are recoverable?  The law permits recovery  of what it called direct damages.  For example, if the  buyer of goods doesn't pay, the seller's direct damages  are recoverable.  But the law also permits the recovery  of indirect damages-- called consequential damages-- if  they are foreseeable.  

For example, if the seller sells low quality goods, and  the buyer loses profits, a certain amount of the profits  may be recoverable.  Frequently, the loss that makes for  a large law suit that is worth litigating over is the  injured party's consequential damages.