〜たい and ほしい: wanting to do, wanting a thing

Japanese splits wanting in two: たい for an action, ほしい for an object. Both behave like い-adjectives, and both are limited to your own wishes.

Also known astai formhoshiiたいほしいwant in japanese

N がほしいですほしい — want (a thing)

Wish

N がほしいです = “I want N” (a thing). The thing wanted takes が.

新しい　車が　ほしいです。

あたらしい　くるまが　ほしいです。

I want a new car.

ほしい is an い-adjective meaning “wanted/desirable”. The desired object is marked with が. It describes the speaker's own wish (or, in a question, the listener's).

In the textbooksMinna I, lesson 13

V-ますstem + たいです〜たい — want to do

Wish

Replace ます with たいです to say “want to (do)”: 行きたいです.

日本へ　行きたいです。

にほんへ　いきたいです。

I want to go to Japan.

Take the ます-stem (行きます → 行き) and add たいです to express “want to do”. たい conjugates like an い-adjective (negative 行きたくないです). The object may take を or が.

In the textbooksMinna I, lesson 13 Genki I, lesson 11