What is the difference between "on" and "one"?

The words on and one are often confused because they are easy to mistype. But what is the difference?

On is a preposition meaning "positioned at the upper surface of, touching from above".

One means "the integer greater than zero and less than two" when used as a number. One is also used as a pronoun meaning "a single individual".

It's easy to mistype one and on, but these two words have very different meanings. Let's take a closer look at each of them.

On is a preposition with several meanings. The most common meaning is "atop" (e.g. the book is on the table). It can indicate contact with a noun (e.g. I cut my finger on the paper) or refer to specific location or time. As an adjective, on means the opposite of off. Some synonyms of on are: active, atop, about, at length, in use, functioning.

Examples of "on":

The cat sat on the mat.
I was on my way to school when the trouble started.
Can you switch the machine on?

One is a number. It is greater than zero and less than two. It can also be a pronoun to refer to a single individual. As an adjective, one refers to an singular noun (e.g. one day). Some synonyms of one are: single, singular, sole, only.

Examples of "one":

It only takes one rotten apple.
Do you want one or two sandwiches in your lunchbox?
I'd like one of those to go, please.

Which is correct, "on the other hand" or "one the other hand"?

The correct expression is "on the other hand" – e.g. I like chocolate, but on the other hand, I hate gaining weight!

Which is correct, "on the basis of" or "one the basis of"?

The right expression is "on the basis of" – e.g. On the basis of the evidence, they installed two solar panels instead of three.

Is the phrase "and so on" or "and so one"?

The correct phrase is "and so on" – e.g. There are many tenses in the English language: the past simple, the past continuous, the past perfect, the present simple, and so on...