Python provides lambda functions, which are a way to write one-liner custom functions so that we can perform certain tasks on a DataFrame's column(s) or the entire DataFrame. Lambda functions are similar to the traditional functions that are defined using the def keyword but are more elegant, are more amenable to apply on DataFrame columns, and have lucid and crisp syntax, much like a list comprehension for implementing for loops on lists. Let's look at how lambda functions are defined and applied.