What it means
たい expresses the speaker's desire to do an action, meaning “want to...” or “would like to...”. It attaches to the verb masu-stem, such as 食べ from 食べます. The resulting form behaves like an i-adjective, so it can be made negative or past when needed. The familiar form is common in plain statements, while たいです is the normal polite version.
Usage note
たい usually describes the speaker's or the subject's desire. For a third person's desire, Japanese commonly uses a form such as たがっています rather than directly stating たい. Do not attach たい directly to the dictionary form.
How to use it
私はりんごを食べたいです。
I want to eat an apple.
私はりんごを食べたい。
I want to eat an apple.
Example sentences
週末に新しい公園を歩きたいです。
I want to walk in a new park this weekend.
夏休みに北海道へ行きたいです。
I want to go to Hokkaido during summer vacation.
仕事のあとで温かいお茶を飲みたいです。
I want to drink warm tea after work.
図書館で日本の昔話