In SharePoint, DOM Manipulation refers to modifying the structure of a SharePoint page after it has finished loading on the client's side. In General, DOM Manipulation can refer to any technique that modifies the Document Object Model (DOM) of any given webpage.

DOM Manipulation refers to dynamically altering elements withing the Document Object Model (DOM). In most cases, some form of JavaScript or JavaScript Framework is used to modify a page's structure after loading.

In SharePoint, this is most often done to overcome or replace some built-in functionality, or to remove some built-in functionality that a particular business does not want to expose to their users.