Generator expressions in Python are a concise way to create generators, which are iterators that yield items one at a time and only when required. They are similar to list comprehensions but use parentheses instead of square brackets. This makes them more memory-efficient, as they generate items on-the-fly rather than storing them all in memory at once.

For example, a generator expression to create a sequence of squares can be written as follows:

squares = (x**2 for x in range(5))

You can iterate over this generator using a loop or convert it to a list if needed:

for square in squares:
    print(square)

Generator expressions are particularly useful when dealing with large datasets or when you want to improve the performance of your code by reducing memory usage. They allow for lazy evaluation, meaning values are produced only when requested, which can lead to significant performance improvements in certain scenarios ⁴⁵.

If you have more questions about generator expressions or related topics, feel free to ask!