〜たい

Meaning

Expresses the speaker's desire; a question can ask about the listener's desire.

Formation

1. Remove ます: 行きます → 行き + たいです.
2. する → したい; 来る → 来たい（きたい）.
3. It conjugates like an i-adjective: たくない, たかった.

When to use it

Personal desire

The speaker says what they themselves want to do.

Question

With か or rising intonation, it asks what the listener wants.

Important notes

• A third person's inner desire is not normally stated directly; 〜たがっている is learned later for that purpose.
• The object usually takes を, but が is also possible: 水が飲みたい.

Common mistakes

• Do not attach たい to the dictionary form: 行くたい is wrong; use 行きたい.

Similar grammar

• Nがほしい〜がほしい is wanting an object; 〜たい is wanting to perform an action.
• Vる／Vない + つもりだ〜つもり describes a formed intention, not merely a desire.
• Vます + に行く／に来る〜に行く gives the purpose of movement: going somewhere in order to act.