In Python, a set is an unordered and mutable collection of unique elements. Sets are defined by placing elements inside curly braces {} and separating them with commas. Sets automatically eliminate duplicate values.

Example:

        
# Creating sets
fruits_set = {"apple", "orange", "banana"}

# Adding elements to a set
fruits_set.add("grape")

# Removing elements from a set
fruits_set.remove("orange")

# Set operations
vegetables_set = {"carrot", "broccoli"}
groceries_set = fruits_set.union(vegetables_set)
        
    

In the example above, fruits_set is a set containing unique fruit names. The add method adds a new element ("grape") to the set, and the remove method removes an element ("orange"). Set operations like union combine two sets to create a new set without duplicates.