A race condition or race hazard is the condition of an electronics, software, or other system where the system's substantive behavior is dependent on the sequence or timing of other uncontrollable events. It becomes a bug when one or more of the possible behaviors is undesirable.

Anomalous behavior due to unexpected critical dependence on the relative timing of events. For example, if one process writes to a file while another is reading from the same location then the data read may be the old contents, the new contents or some mixture of the two depending on the relative timing of the read and write operations. A common remedy in this kind of race condition is {file locking}; a more cumbersome remedy is to reorganize the system such that a certain processes (running a daemon or the like) is the only process that has access to the file, and all other processes that need to access the data in that file do so only via interprocess communication with that one process. As an example of a more subtle kind of race condition, consider a distributed chat network like IRC, where a user is granted channel-operator privileges in any channel he starts. If two users on different servers, on different ends of the same network, try to start the same-named channel at the same time, each user's respective server will grant channel-operator privileges to each user, since neither will yet have received the other's signal that that channel has been started. In this case of a race condition, the "shared resource" is the conception of the state of the network (what channels exist, as well as what users started them and therefore have what privileges), which each server is free to change as long as it signals the other servers on the network about the changes so that they can update their conception of the state of the network. However, the latency across the network makes possible the kind of race condition described. In this case, heading off race conditions by imposing a form of control over access to the shared resource -- say, appointing one server to be in charge of who holds what privileges -- would mean turning the distributed network into a centralized one (at least for that one part of the network operation). Where this is not acceptable, the more pragmatic solution is to have the system recognize when a race condition has occurred and to repair the ill effects. Race conditions also affect electronic circuits where the value output by a logic gate depends on the exact timing of two or more input signals. For example, consider a two input AND gate fed with a logic signal X on input A and its negation, NOT X, on input B. In theory, the output (X AND NOT X) should never be high. However, if changes in the value of X take longer to propagate to input B than to input A then when X changes from false to true, there will be a brief period during which both inputs are true, and so the gate's output will also be true. If this output is fed to an edge-sensitive component such as a counter or flip-flop then the temporary effect ("glitch") will become permanent. (2002-08-03)

In numerical analysis, the condition number of a function measures how much the output value of the function can change for a small change in the input argument. This is used to measure how sensitive a function is to changes or errors in the input, and how much error in the output results from an error in the input.

The Abbe sine condition is a condition that must be fulfilled by a lens or other optical system in order for it to produce sharp images of off-axis as well as on-axis objects. It was formulated by Ernst Abbe in the context of microscopes.

Nanocar Race is an international scientific competition with the aim of testing the performance of molecular machines and the scientific instruments used to control them. The race of the molecules takes place on a 100 nanometer track and was held for the first time in Toulouse on 28 and 29 April 2017.

A symlink race is a kind of software security vulnerability that results from a program creating files in an insecure manner. A malicious user can create a symbolic link to a file not otherwise accessible to them.

The Dinaric race, also known as the Adriatic race, were terms used by certain physical anthropologists in the early to mid-20th century to describe the perceived predominant phenotype of the contemporary ethnic groups of southeast Europe (a sub-type of the Caucasoid race).

Conditions races are horse races in which the weights carried by the runners are laid down by the conditions attached to the race. Weights are allocated according to the sex of the runners, with female runners carrying less weight than males; the age of the runners, with younger horses receiving weight from older runners to allow for relative maturity, referred to as weight for age; and the quality of the runners, with horses that have won certain values of races giving weight to less successful entrants.

A race stage, leg, or heat is a unit of a race that has been divided in several parts for the reason such as length of the distance to be covered, as in a multi-day event. Usually, such a race consists of "ordinary" stages, but sometimes stages are held as an individual time trial or a team time trial.

Playing the race card is an idiomatic phrase that refers to the exploitation by someone of either racist or anti-racist attitudes in the audience in order to gain an advantage. It constitutes an accusation of bad faith directed at the person or persons raising concerns as regards racism.