When you are issued a US patent, you receive an official copy of the patent from the US patent office. This official copy is bound in a folder with a message from the Director of the US Patent and Trademark Office printed on the cover.  This message details the rights granted with the issuance of this patent.  Click here to see a copy of that coverpage. 

The key statement as to the rights granted to the inventor (or his assignee) is:

Therefore, this United States Patent grants to the person(s) having title to this patent the right to exclude others from making, using, offering for sale, or selling the invention throughout the USA or importing the invention into the USA for the term set forth below, subject to the payment of maintenance fees as provided by law.

If the patent application was made after June 8, 1995, the term of the patent is 20 years from the filing date.  If the inventor has assigned the patent to another person or entity, then all his rights are transferred to the assignee.

     What exactly is the “invention” in a patent?

The “invention” for which the inventor (or his assignee) has the right to stop others from making or marketing is what is described in the Claims at the end of the patent.

     Does the patent give the inventor (or his assignee) the right to make or  market his invention?

No, not necessarily.  The rights granted the inventor (or his assignee) merely permits him to stop others from making or using this invention.  There may be cases where he would not be able to make or market his invention.  One such case is the existence of prior patents covering technologies necessary for the construction or operation of the invention.  In such case, the inventors (or assignees) of the prior patents can stop the new inventor from making or marketing his invention.