Slicing is a programming technique used to access a specific portion of a data structure, such as a list or an array. It allows users to extract a subset of elements by specifying a start and end index. For example, in the programming language Python, slicing can be done using the syntax `list[start:end]`, which returns elements from the start index up to, but not including, the end index. This method is particularly useful for manipulating data efficiently, as it enables quick retrieval of elements without the need for loops. Slicing can also be applied to strings, making it a versatile tool in various programming tasks.