A patent gives the owner the right to:
“keep others from making her invention”
Why? Patents confer exclusionary rights. The Trade Related Intellectual Property Aspects (TRIPs) Agreement, which was agreed upon in 1994 by the member states of the World Trade Organisation (WTO), states that the patent right holder can prevent others from “making, using, offering for sale or importing for those purposes” the invention.
Because patent claims in one patent can dominate claims in a second patent, the rights holder may not always be able to practice her invention without the consent of the first rights holder. For example, if one patent claims “A chair” , and a second patent claims “A 3-legged chair”, the second owner can not make her invention without permission from the owner of the first patent. Conversely, the owner of the first patent could not make 3-legged chairs without permission of the owner of the second patent, but could make any other kind of chair.