会う・遭う

1. 会う - the standard meeting

This is the kanji which is used 90% of the time. It implies a social encounter or a planned meeting between people. It carries a neutral or positive connotation.

• Meaning: To meet a person, to see a friend.
• Example: 週末に友達と会う約束があります。

2. 遭う - the unfortunate encounter

This kanji specifically denotes a chance encounter with something negative, accidental, or disastrous. It is often used for accidents, rain, or being victimized.

• Meaning: To encounter, to run into (trouble/disaster).
• Example: 旅行中に盗難に遭った。

目(め)に遭(あ)う is a fixed expression in Japanese. Even though 目(め) usually means “eye”, in this context it refers to a “point in time” or an “experience.” It almost exclusively refers to negative experiences.