Used in the form 'A vs B' to indicate opposition or comparison between two sides (e.g., A vs B).
決勝は日本対ブラジルの対戦だ。
The final is Japan vs. Brazil.
来週の試合は地元チーム対招待チームで行われる。
Next week's match will be held between the local team and the invited team.
この意見書では労働者側対会社側の主張を整理している。
This brief organizes the claims of the workers versus those of the company.
Placed between numbers as 'X to Y' to indicate a score, ratio, or vote (contrasting two numerical values).
試合は4対2で終了した。
The match ended 4 to 2.
賛成は320、反対は180で、結果は320対180だった。
There were 320 in favor and 180 against; the result was 320 to 180.
この商品の男女比は3対1だ。
The male-to-female ratio for this product is 3 to 1.
Used as a prefix to mean 'toward', 'against', or 'in relation to' (e.g., 対外: toward foreign countries; 対策: countermeasure).
政府は対外政策を見直すと発表した。
The government announced it will review its foreign policy.
会社はクレームに対して迅速に対処した。
The company responded promptly to the complaints.
対日輸出が増加している。
Exports to Japan are increasing.
Related to the idea of being on equal footing or having equal terms (often appears in compounds like 対等).
取引先とは対等な関係を築きたいと考えている。
We want to build an equal relationship with our business partners.
交渉は双方が対等な立場で行われた。
The negotiations were conducted with both sides on equal footing.
Indicates something opposite or facing (as in 'the opposite side' or 'facing one another'), seen in compounds like 対岸 or 対面.
川の対岸に古い神社が見える。
You can see an old shrine on the opposite bank of the river.
彼は席の対面に座って話した。
He sat opposite the seat and talked.