Scrying was the magical ability to use one's senses to experience events far away, though typically within the same Realm. This ability could be performed with a variety of methods, but many divination Spells of the scrying subSchools of Magic created a sensor that sent the caster information. The sensor had the sensory acuity of the caster and acted as though it were a separate, independent organ. Any intelligent creature could notice an active magical sensor, and the sensor could be dispelled by other spellcasters.
For all versions of scrying, the chance of success was increased by knowledge of the subject. If the subject was a location, then scrying was much more likely to succeed if the caster had been to the location rather than having a picture or having it described to him or her. If the subject was a sentient being, then the more familiar the caster was with the person the better. Additionally, having a personal possession, something that was worn by the subject, or an actual piece of the subject (hair clipping, a vial of blood, etc.) also improved the chance for success.
Scrying could not penetrate lead, with lead sheeting or high concentrations in natural rock being effective barriers.