This is the 960th most frequent Japanese word.
出現
Appearance; emergence.
The word 出現 is used here to mean 'to appear or emerge', emphasizing the introduction of a new item or concept into the market.
市場に新しいスタイルのスマートフォンが出現した。
A new style of smartphone emerged on the market.
Here, 出現 signifies the sudden manifestation of something unusual or unexpected.
古代の神殿では、突然不思議な光が出現したと記録されている。
It is recorded that a mysterious light suddenly appeared in the ancient temple.
In this context, 出現 is used to describe the surfacing or becoming apparent of a significant issue over time.