denotes your own desire to do something. It can only be used for self, and not for what someone else wants.
タクシーに乗りたい I want to take a taxi
学校へ行きたくない I don't want to go to school
becomes 形容詞
So it can be further conjugated.
食べたくなった I became wanting to eat.
Can take object of emotion.
'wanting' fits the category of Describing emotions, meaning it can take an object of emotion. This means that what you want is not denoted with を, but with Object of emotion. An alternative reading of this is that it turns into a 形容詞, which means that it also becomes intransitive.
Choose something from options
ご飯が食べたい。 I want to eat rice.
Do a routine action
今日はバスケットボールがしたいです Today, I want to play basketball.
transitivity
Using a transitive verb in its たい form retains Transitivity. It allows to use either the が or を particle to be used in the sub-sentence, depending on the thing you want to emphasise.
魚が食べたい。 The fish is something I want to eat.
魚を食べたい。 I want to eat fish