To
In short
To is a preposition used to show direction, purpose, or a connection between words. It is one of the most common words in the English language.
In plain words
We use this word to point towards a place, a person, or a goal. It can also be used before a verb to explain why someone is doing something. It acts like an arrow that connects an action or a person to a destination or a reason.
A simple example
If you are walking towards a shop, you say, I am going to the shop. If you are doing something for a reason, you might say, I exercise to stay healthy.
Why it matters
Without this word, it would be very hard to explain movement or intentions. It helps people understand where you are going and what your goals are in a sentence.
Easy to mix up
People often mix up to with two or too. Two is a number, too means also or extra, but to is used for direction and purpose.