(1) What is OFAC? OFAC stands for the Office of Foreign Assets Control which is an office of the US Department of the Treasury administering and enforcing economic and trade sanctions based on US foreign policy and national security.
(2) Why do I need to know about OFAC and its policies? OFAC has prohibited certain transactions with certain countries and group of individuals associated with those countries. Some of these targeted foreign countries include, Cuba, Iran, Ukraine/Russia, Syria, Balkans, Burma, Cote d’Ivoire (Ivory Coast), Somalia, Lebanon, Libya, Sudan, Venezuela, Yemen, Zimbabwe, and etc. Any US person (US Citizen and Green Card holders regardless of where they are located, and all persons located in the United States and US entities and their foreign branches) must comply with OFAC regulations in dealings with these countries. Therefore it is crucial to know what is allowed and not allowed by OFAC in such dealings so one is certain they are not breaking the rules.
Individuals and businesses could apply for a license (permission) from OFAC as an authorization to engage in a transaction with the targeted foreign country that would otherwise be prohibited. For example an individual who has property (money, valuable items, inheritance, etc.) in the targeted foreign country could obtain an OFAC license to get authorization to transfer the property to US or do whatever dealings is necessary to sell the property in the targeted foreign country and bring the proceeds to US.
(3) What types of OFAC Licenses are out there? There are generally two types of licenses issued by OFAC, general license and specific license.
General License:
A General License is an already given approval to certain types of transactions. For example bringing money from Iran to United States which was inherited and is in the form of cash generally does not need a license. You also generally do not need a license for transferring money to US to yourself or your children for personal use. However, have in mind that even for general license transfers you need to make sure the money is not being transferred from a sanctioned bank in the targeted foreign country. If it is being transferred from a sanctioned bank the funds could be blocked and it would be very difficult to get OFAC to release the block. A complete list of designated sanctioned banks for each targeted foreign country could be found on US Department of the Treasury’s website.

Specific License:
A Specific License is a written document issued by OFAC to a particular US person or US entity authorizing them to engage in the authorized transactions specified in the license. OFAC license application is not a form that you can fill in but is a formal written letter addressed to OFAC describing in details the transactions for which one needs approval. The details should include the type of transaction, type of dealings and procedures needed to conduct the transaction, names and addresses of all the persons involved, names of the banks involved and etc. The more information you include in the letter the more likely your application would not be denied. And have in mind OFAC license would only give approval to transactions and dealings you have specifically listed on your letter so the more details in your letter the easier it is for you to go ahead with your transaction once the license is granted.
Persons engaging in transactions and dealings that are authorized under their general or specific licenses must make sure that they strictly follow all the conditions and restrictions of their licenses.
(4) What are some of the penalties for violating the laws of OFAC? Violations could have severe consequences. Depending on the violation and specific facts of each case, there could be criminal fines, imprisonment, and civil penalties.

Some information about transferring assets from Iran to United States:
(1) How to transfer assets from Iran to United States without violating rules of Iranian Transactions Regulations?
US persons have to follow the rules issued by OFAC in relation to dealings with Iran. Individuals and businesses could apply for a license (permission) from OFAC as an authorization to engage in a transaction with Iran that would otherwise be prohibited. For example an individual who has property (money, valuable items, inheritance, etc.) in Iran could obtain an OFAC license to get authorization to transfer the property to US or do whatever dealings is necessary to sell the property in Iran (hiring agents, lawyers, accountants in Iran) and bring the proceeds to US.
(2) What about brining inherited money from Iran? If it is only money in the form of cash inherited (non-commercial family remittance), you could bring it to United States without a need for a specific license. OFAC has given a general license for these sorts of transactions which means approval is already granted and there is no need for applying for a license for this specific transaction. Although OFAC still requires you to follow the financial restrictions. Due to sanctions and prohibitions in the Iranian Transactions Regulations wire transfers cannot be done directly from an Iranian Bank to a US bank. What can be used is services of a third party bank like one in Dubai or Turkey or Europe that accepts the money from an Iranian bank (which is not on the list of OFAC SDN designated banks (is not a sanctioned bank)) and then transfer it to a US bank.
However, be aware that if the inherited item is not money but in the form of a valuable like a business or a property then OFAC requires you to apply for a specific license if you are planning on disposing the property and bringing the proceeds to US. You would need a specific license to do what is needed in Iran to sell the property and to bring the cash from the sale.