One-to-one

One-to-one or one to one may refer to:

Mathematics and communication

One-to-one function, also called an injective function
One-to-one correspondence, also called a bijective function
One-to-one (communication), the act of an individual communicating with another
One-to-one (data model), a relationship in a data model
One to one computing (education), an initiative for a computer for every student
One-to-one marketing or personalized marketing, an attempt to make a unique product offering for each customer

One to One (Apple), Apple's personal training service
One 2 One, a defunct British mobile telecommunications company, which became T-Mobile UK
One to One (TV series), an Irish TV series