One to one communication usually takes place between two people, either directly that is face to face or on the telephone or via email writing and lots more.
There are a lot of things to be kept in mind before we start talking to someone and moreover it is very important that the person with whom we are communicating must understand and able to think of what you are speaking to them.
The verbal way of communicating is nothing but by speaking to each other. Here, no actions and gestures are occurring mostly but the words are being exchanged. The conversation between two people can occur in a lot of ways but it's all casual and no rehearsal is done or practiced. Speak on the number of topics and be gentle and courteous.
There can be one to one communication in telephone as well and even via emails.
This can happen in the nonverbal method as well. For example, sign language or deaf people trying to communicate to each other. Even body language plays an important role. The way we move our hands and legs. The way we shake our head also matters and shows the interest of the opposite person. Using time also two people can communicate. Using appearance, we can communicate non-verbally.
One to one communication can also be seen in the interview where the interviewer is talking face to face with the person and there are questions being asked. They need to manage the interview carefully and they can easily pass the interview.