Screening, in general, is the investigation of a great number of something (for instance, people) looking for those with a particular problem or feature. One example is at an airport, where many bags get x-rayed to try to detect any which may contain weapons or explosives. People are also screened going through a metal detector. Even though the procedure aims at a large number of screens, it is always equivalent to sampling in statistics, because the complete population is almost always inaccessible for screening.

Screening has other, more specific meanings:

• In color printing, screening refers to a process that represents lighter shades as tiny dots, rather than solid areas, of ink
• In physics, electric field screening refers to the dampening of an electric field by mobile charges
• In atomic physics and chemistry, screening effect refers to the observation that electronic properties of atoms are better described if atoms had a lower effective nuclear charge than that would be otherwise expected from the number of protons present.
• Screening (economics)
• Screening (medicine)
• Screening for pharmacological activity during drug discovery
• Part of the process of Environmental impact assessment.
• Hampering an opponent's attempts at reconnaissance
• A type of tactic (sometimes legal, sometimes not) in sport games such as basketball or volleyball
• Separation of mixtures of particle sizes into more distinct ranges of particle sizes using mesh screens.
• A screening can refer to the display of a film in a movie theatre or screening room, for some special purpose such as testing or critical review.

Source: adapted by the editor from Wikipedia, the free encyclopedia under a copyleft GNU Free Documentation License (GFDL) from the article "Screening"