A strong drink is any kind of alcoholic drink.
It was forbidden to:
Levites who were entering the tent of meeting (Leviticus 10:9)
Those taking the Nazirite vow (Numbers 6:3; Judges 13:4–14)
Kings and rulers (Proverbs 31:4)
John the Baptist (Luke 1:15)
The writer of Proverbs 20:1 suggests that the wise man does not become drunk by it. Isaiah warns against those who are addicted to it (Isaiah 5:11, 22). Strong drink was used as an offering in the Levitical sacrifice (Numbers 28:7). It was allowed during the feast when tithing (Deuteronomy 14:26).