This article comes from the website of VonSiedels with their permission

What is a patent?
A patent is a limited monopoly granted by the state to an inventor, or other person entitled to the invention, in exchange for a full disclosure of the invention to the public. This monopoly entitles the patent holder to prevent others from using the invention in any practical manner for the duration of the patent so that only the patent holder enjoys any profit or advantage that the invention affords for the period. After expiry of the period members of the public is free to use the invention.
Is my invention patentable?
To be patentable in South Africa an invention must be new, inventive and useful.
“New” means that the invention has not been made available to the public anywhere in the world – by word of mouth, by use, in any printed publication, or in any other way – before a first application is made for a patent. It is difficult to establish whether an invention is, in fact, new, but novelty may be assessed by carrying out searches through existing printed publications that include previously published patent specifications.
“Inventive” means that the invention must not be obvious to a person of ordinary skill in the art to which the invention relates. Put differently, the invention must not be so similar to what was available or used previously that it required little or no ingenuity to make the invention; that is to say, it must involve an inventive step. For example, it would be obvious to make an article that was previously made exclusively of metal in a plastic material, if there were no special and unforeseeable advantages to making it in plastic.
“Useful” means the invention must be capable of being applied in trade, industry or agriculture.
In addition to the above three requirements, there are certain “inventions” which cannot be patented in South Africa. The most important of these are pure business methods and computer programs. This prohibition, however, does not extend to inventions that merely make use of business methods or computer programs, while not constituting business methods or computer programs as such. We urge you to contact us if you are uncertain as to whether an invention constitutes a pure business method or computer program.
Lastly, a method of treatment of the human or animal body by surgery, therapy or diagnosis is not patentable in South Africa.
How long does a patent last?
A South African patent lasts 20 years from the date of application, subject to the payment of annual renewal fees as from the third anniversary of the filing date.
How easily can someone else get around my patent?
The scope of protection afforded by a patent is defined by the patent claims. A well-drafted set of patent claims will prevent others from being able to reverse-engineer the invention by including or excluding inessential features while still using the basic idea of the invention. This is why the use of patent attorneys who are experienced in the drafting of patent specifications is so important.
What can I do with a patent?
A patent is property and may be sold (by way of assignment) or licensed for use by others. Alternatively, a patent can be used defensively to prevent others from exploiting the invention, provided the patent holder exercises with the invention to an adequate extent.
How do I apply for a patent?
A patent application is made by filing a patent specification, together with the necessary forms and government fees, at the Patent Office in Pretoria. The patent specification, which includes a description of the invention as well as any drawings which may be necessary for a clear understanding of the description, may be either a provisional or complete patent specification.
If the invention is not yet in its final form it is preferable to file a provisional patent application first, and then a complete patent application within 12 months, because improvements made to the invention can be incorporated into the complete patent specification. A complete application may be in the first instance if sufficient information about the invention and its implementation are available.
If given a description of the invention, we will prepare the patent specification and the necessary forms and file a patent application on your behalf. All the administrative functions will be carried out by our offices.
How do I get patents in other countries?
A patent application must be filed in each country in which protection is sought. However, in respect of most countries in the world, corresponding foreign patent applications can be filed within 12 months from the first patent application in terms of the Paris Convention.
The Patent Cooperation Treaty (PCT) provides a mechanism to delay the filing of individual foreign applications by a further 18 months and also provides a facility for tailoring a patent specification according to the results of an international search and examination. Should you require patent protection in more than 2 or 3 foreign countries, we usually recommend filing a PCT patent application, unless it is essential that granted patents be obtained in the foreign countries as soon as possible.
A PCT application must be filed within 12 months from the date of first filing a patent application, regardless of whether the first patent application is a provisional or complete South African patent application.
What are the costs involved?
The cost involved in preparing and filing a provisional or complete patent application will vary from case to case and will depend on the length of the patent specification and that will, in turn, depend on the technology and the type of invention.