A two-in-one computer is a computing device that achieves the dual functionality of a laptop computer and a tablet device. In most cases, these devices resemble a laptop computer, but the keyboards can either be folded away or detached entirely.
Techopedia explains Two-In-One Computer
Two-in-one computers solve various end-user problems involving portability, ease-of-use and versatility. By combining a tablet interface with a computer keyboard, the two-in-one computer gives users the option of either working on the device like a tablet or folding out the keyboard and using alphanumerical input to interact with the computer.
Part of the popularity of the two-in-one computer is the fact that early tablets did not have a physical keyboard and thus were difficult to type on. This problem results in "output deficiency"; in other words, although it is easy for smartphone or tablet users to get all kinds of information over the Internet or open up files, it is extremely difficult for them to develop polished, quality output quickly without a physical keyboard.
Moreover, the popularity of the two-in-one computer provides a glimpse of the interfaces of the future. Some experts say that a speech-to-text interface or some other resource may soon replace the alphanumeric keyboard and change the way individuals use computing devices. Until then, the two-in-one computer offers consumers a number of advantages, including the portability of the tablet, a tablet-style interface and the versatility of a keyboard. A two-in-one computer may not be able to support intensive data entry very well, but for many users, it is a lot easier than tapping a touchscreen for input.