You use to when indicating the place that someone or something visits, moves towards, or points at.

If you go to an event, you go where it is taking place.

If something is attached to something larger or fixed to it, the two things are joined together.

You use to when indicating the position of something. For example, if something is to your left, it is nearer your left side than your right side.

When you give something to someone, they receive it.

You use to to indicate who or what an action or a feeling is directed towards.

You use to with certain nouns and adjectives to show that a following noun is related to them.

If you say something to someone, you want that person to listen and understand what you are saying.

You use to when indicating someone's reaction to something or their feelings about a situation or event. For example, if you say that something happens to someone's surprise you mean that they are surprised when it happens.

You use to when indicating the person whose opinion you are stating.

You use to when indicating what something or someone is becoming, or the state or situation that they are progressing towards.

To can be used as a way of introducing the person or organization you are employed by, when you perform some service for them.

You use to to indicate that something happens until the time or amount mentioned is reached.

You use to when indicating the last thing in a range of things, usually when you are giving two extreme examples of something.

If someone goes from place to place or from job to job, they go to several places, or work in several jobs, and spend only a short time in each one.

If someone moves to and fro, they move repeatedly from one place to another and back again, or from side to side.

You use to when you are stating a time which is less than thirty minutes before an hour. For example, if it is 'five to eight', it is five minutes before eight o'clock.

You use to when giving ratios and rates.

You use to when indicating that two things happen at the same time. For example, if something is done to music, it is done at the same time as music is being played.

If you say 'There's nothing to it', 'There's not much to it', or 'That's all there is to it', you are emphasizing how simple you think something is.

If you push or shut a door to, you close it but may not shut it completely.