Reduction of a work of authorship into some tangible form, which is required for copyright protection in many countries.
Fixation is one of the fundamental tenets of U.S copyright law, and plays an important role in that of other countries as well. Such fixation might include writing something down, recording it, placing it on film, or making it. For legal systems with a fixation requirement, it is the fixing that changes an idea into a copyrightable work.
The fixation requirement can lead to some interesting results for creative art form that do not normally record or otherwise fix their expression, such as dance choreography, stand-up comedy, recipes, or the performance of live music. U.S. law has a specific statutory exception mandating that performers of live music still hold rights in it even if they are not recording it, and that others cannot record the performance without their permission.
Perhaps surprisingly, some jurisdictions do not have a fixation requirement, choosing instead to vest copyright in a work using other criteria. For example, Swiss law requires only that a work have “individual character”. Other countries with no fixation requirement include Sweden, Japan, Spain and France, among others. The Berne Convention does not require fixation, although a country may do so in its internal copyright laws without violating the Convention.