I am creating a list of words according to parts of speech, and I don't know if 'to' is a preposition or a conjunction.
'to' like in: She went to the party.
They want to learn.
Thanks for your help
To is a preposition.
Uses of "to"
To occurs with several classes of verbs.
1. verb + to + infinitive
Verbs in this group express willingness, desire, intention, or obligation.
willingness: be willing, consent, refuse
desire: desire,
want, wish, like, ask, request, prefer
intention: intend, plan, prepare
obligation: be obligated, have, need
Examples:
(9) I refuse to allow you to intimidate me with your threats.
(10) I'd like to ask her how long she's been skiing.
(11) I plan to graduate this summer.
(12) Henry had to pay his tuition at the Bursar's office.
2. In other cases "to" is used as an ordinary preposition.
verbs of communication: listen, speak (but not tell), relate, appeal (in the sense of 'plead,' not 'be attractive')
verbs of movement: move,
go, transfer, walk/run/swim/ride/drive/ fly, travel
For more information, click on the following link:
Prepositions of Direction: To, On (to), In (to)
and a useful exercise:
https://www.usingenglish.com/handouts/349.html