What is 'abc'?

In programming, "abc" can refer to different things depending on the context:

1. String Literal: In many programming languages, "abc" is simply a string of characters. For example, in Python, you can define it as:

   my_string = "abc"

2. Abstract Base Class (ABC): In Python, the abc module is used to define abstract base classes. An abstract base class is a class that cannot be instantiated and is meant to be subclassed. It defines a common interface for its subclasses.

3. Alphabet: In a broader sense, "abc" can refer to the first three letters of the alphabet, often used in educational contexts.

If you have a specific context in mind, please let me know!