First of all, it s a company Incorporated in a country wich can make business only outside the country where it is Incorporated .
Depends on the country you incorporate the company, you will be exempt of tax.
It s also used to to protect your asset.
Last benefits is to stay anonymous.
There is not that much of a difference in the company operation other than you have to keep and maintain accounting in the local one and in most offshore corps you don't have to do that!
Complete confidentiality of operational processes – businesses that want to enjoy complete privacy with regards their operational processes can benefit from this structure.
Exemption from personal and corporate tax – offshore establishments are not required to pay corporate and personal tax.
There is a better protection when it comes to legal action against your company as well as creditor protection. It's most often very costly to run any legal case against a offshore company!