importance of newline = "" in writing the csv file

newline.py

# opening a file without newline = ""
import csv
with open('something.csv','w') as f:
    writer = csv.writer(f)
    writer.writerow(["one", "two", "three"])
    writer.writerow(["one", "two", "three"])

# as I am writing on windows system it uses "\r\n" line endings on write
# so an extra \r (carriage return) is added
with open('something.csv','r') as f:
    reader = csv.reader(f)
    for row in reader:
        print(row)
        
"""
['SN', 'Movie', 'Protagonist']
[]
['SN', 'Movie', 'Protagonist']
[]
"""