Weak typing refers to a programming language's flexibility in handling different data types. In weakly typed languages, variables can be easily changed from one type to another without strict enforcement. For example, a variable that initially holds a number can later be assigned a string without causing an error. This can lead to unexpected behavior if not managed carefully. Languages like JavaScript and PHP are examples of weakly typed languages. While this flexibility can make coding quicker and easier, it can also introduce bugs and make debugging more challenging, as the programmer must be more vigilant about the types of data being used.