Want 這個動詞有三個主要意思：1.「要，想要」：He wants you to see him in Taipei without fail. (他要你務必在台北見他)；2.「缺乏，缺少」：This deck of cards wants a nine of clubs. (這副牌缺了一張梅花9)；3.「應該」(ought to or should)：You want to tell him the truth. (你應該把實情告訴他)。第1和第2個意思無疑地是標準英語，而第三個意思通常僅限用於口語和非正式寫作。
我們知道，當 want 意為「要，想要」時，它的後面是緊接著不定詞結構，而不是接 for：I want you to go. (我要你去) – 不是I want for you to go.。然而，當 want 和不定詞在句中被分開時，這時候就要使用 for：What I want is for you to go. (我想要的是你去)；I want very much for you to go. (我很想要你去)。當意為「缺乏，缺少」時，它通常接 for：They’ll not want for anything now that they’ve inherited his estate. (既然他們已繼承他的遺產，他們將一切無缺了)。
Want down, want in, want into, want off, want out, want up 這些片語最好的情況僅能被視為方言，但大多數情況都被視為非正規英語，不合語法，應避免使用：Could you hold on a moment? The kid wants down [up]. (請稍等一會兒，好嗎? 孩子想要下來/上來)；The cat’s at the back door and wants in [out]. (貓在後門想要進來/出去)；She wants into Cambridge University. (她想上劍橋大學)；He accepted the appointment just last month, but now he wants out. (他上個月甫接受這項職位，但現在卻想掛冠求去)；She wants off at the next stop. (她想在下一站下車)。正規英語都會在 want 後面加上不定詞再加介系詞而不會僅單獨使用 down, in, into, off, out, up (即 wants to come in, wants to get down, into, out, off, up)，但不少人卻仍經常在輕鬆的場合不經意地使用這些片語。
Want 後面不可接 that 子句，所以像 She wants that you should come upstairs. (她要你上樓) 這樣的句子都是非正規英語，不合語法。如上述，want 後面接不定詞才是合乎語法的正規英語：She wants you to come upstairs.。