たい

たい is an auxiliary verb that is used to express things that you would like to do (want). To use たい, it needs to be added to the same conjugation base form of a verb that ます would be attached to.

When using たい, the thing that is 'wanted' can either be marked with を, or が. The difference in nuance is that something marked with が is considered to be wanted more. たい is conjugated in the same way as い-Adjectives, meaning that the negative, past, or past-negative forms may also be used.

たい is only used for expressing things that 'you' want, or repeating information/asking questions about what other people want. It may not be used to make guesses about what other people 'may' want, unless asking them directly.