Parquet is columnar store format published by Apache. It's commonly used in Hadoop ecosystem. There are many programming language APIs that have been implemented to support writing and reading parquet files.
You can also use PySpark to read or write parquet files.
Code snippet
from pyspark.sql import SparkSession
appName = "Scala Parquet Example"
master = "local"
spark = SparkSession.builder.appName(appName).master(master).getOrCreate()
df = spark.read.format("csv").option("header", "true").load("Sales.csv")
df.write.parquet("Sales.parquet")
df2 = spark.read.parquet("Sales.parquet")
df2.show()