Conventional wisdom tells us that great inventions and patent protection go hand in hand because that is one way that companies and inventors can recover and benefit from their investment in R&D, either by monetising their inventions or creating barriers to entry. One would expect this to be especially applicable in the case of breakthrough innovations. So when you read through TIME magazine’s recent article describing the “25 best inventions of 2013” you can’t help but wonder if they are indeed all protected by impregnable patent fortresses.

A patent application does not necessarily cover a product as a whole, but may be directed towards one or more specific product features or components. Therefore, although some inventive products are associated with only one or two applications filed in one or more countries (as appears to be the case for Anki’s driverless toy car and Motorola’s edible password pill), more often than not several applications will be filed, each directed to a different feature of the product. Mission Motors, for example, have a number of US patent applications directed to a variety of features relevant to their electric motorcycle, Mission R, including the frame, power electronics and thermal management of a battery pack.

Other well-protected inventions on TIME’s list include the Atlas Robot for which Boston Dynamics have applications for an actuator system, controlling the jumping of a robot, various robot mechanisms and a reconfigurable robot drive. Second Sight Medical have many patent applications in the field of visual prostheses like the Argus II. Argo Medical have a number of patent applications related to the Rewalk motorised exoskeleton unit. Medtronic have a plethora of applications related to the treatment of diabetes, some of which may be related to their artificial pancreas. And Gasfrac have filed an application for a liquefied petroleum gas fracturing system for waterless fracking in several countries.

The relationship between inventions and patent protection is far from straightforward, and depends on numerous factors.

The first threshold hurdle to overcome is patentability. This requires that an invention be new and inventive. For some inventions it could be tricky to prove novelty and inventiveness making inventions like Dominique Ansel’s croissant-donut, the Cronut difficult to patent. However, a method of preparing a food or beverage can be potentially patentable, as those at the University of Minho would have assumed when filing an application for the method with which their alcoholic coffee is prepared.

A further patentability threshold is subject matter in that certain types of subject matter are generally excluded from patentability. For example pure scientific discoveries or algebraic approaches per se, like Nima Arkani-Hamed’s amplituhedron, are generally not patentable subject matter (even though practical applications could well be).

Patentability of an invention, however, is only one side of the coin. Commercial potential can often be the deciding factor when determining whether to seek protection or not.

The fact that something is a great idea which captures the public imagination (as at least some of these 25 inventions presumably would do) does not guarantee commercial success or even commercial potential. Other factors come into play, such as potential market size and market penetration. If the potential market is small there may be little incentive to invest in patent protection. This might be the case for Gravity’s “lightbox”: an intricate movie set used to simulate light in outer space, or the Plus Pool: an Olympic size swimming pool that also acts as a water filter for the East River in New York City, neither of which appear to have been patented.

On the other hand, in very competitive fields such digital photography, especially the growing field of smartphone photography, it would be fair to assume that at least some of Sony’s numerous lens patents may relate to their smart lens.

It is sometimes possible to protect an invention as a trade secret (a so-called Coke recipe-type scenario). But with improved analytical tools and leakage of information through movement of personnel and industrial espionage this option is becoming less attractive in competitive markets. That said, patents and trade secrets can be used in tandem to good effect in the hands of skilled players.

When an invention passes the patentability threshold and shows properly assessed commercial potential, patents play an increasingly important role. There are still many hurdles ahead, especially in a start-up environment or in the development of a completely new product. These may include sourcing materials, scaling up manufacturing, establishing manufacturing and distribution chains, generating demand through advertising and marketing, and maintaining sources of funding. Of course licensing out the technology is also an option, made more viable with the benefit of patent protection. When an invention ultimately does achieve commercial success, patent protection can and does invariably directly contribute to the return on investment.

So a good guess would be that those inventors of TIME’s “25 best inventions” who have sought patent protection are those who are anticipating or who may have already achieved commercial success. It will be interesting to see how many of these “25 best inventions” go on to achieve widespread commercial success in a few years’ time, and the extent to which patents may be involved in preserving that success.