when do we use 'to'?
to in english
'to' is simply a marker - a sign of the infinitive. So you use it to indicate that this is a verb in infinitive form.
- I love travel - here 'travel' is a noun
- I love to travel - now you use marker to specify that you love the action of travelling.
Usually you can use also the gerund instead of infinitive:
- I love travelling.