Currently I'm using page object design pattern with testing.
Page object is an design pattern.
First you should understand the difference between framework and design pattern.
For that refer this link.
To understand page object design pattern refer this link.
Use Unofficial site for more detail : Do a Google search, you will get a lot info on this link.
Page Object Pattern
According to Selenium official documentation:
Page Object is a Design Pattern which has become popular in test automation for enhancing test maintenance and reducing code duplication.
It is not a framework as frameworks are usually understood as a specific implementation:
A software framework is a universal, reusable software environment that provides particular functionality as part of a larger software platform to facilitate development of software applications, products and solutions. Software frameworks may include support programs, compilers, code libraries, tool sets, and application programming interfaces (APIs) that bring together all the different components to enable development of a project or system
It is a way to represent a webpage in an abstract way.
We "view" a webpage as if it was made of various objects, such as its page title, page URL, page elements (buttons and etc) and various actions we can perform on elements, such as click, drag, navigate and etc.
You can find more comprehensive information on Page Object here: Page Object Model link