• SparkContext is the entry point to Spark.
• Using sparkContext you create RDDs which provided various ways of churning data.
• When a programmer creates a RDDs, SparkContext connect to the Spark cluster to create a new SparkContext object.
• SparkContext tell spark how to access the cluster.
• SparkConf is key factor to create programmer application.

Various ways to create contexts in spark ?

•  Sparkconext
•  Sqlcontext
•  Sparksession
•  Sqlcontext.sparkcontext

.How does Spark Context in Spark Application pick the value for Spark Master?

That can be done in two ways.

• Create a new SparkConf object and set the master using its setMaster() method.
  • This Spark Configuration object is passed as an argument while creating the new Spark Context.
    SparkConf conf = new SparkConf().setAppName(“JavaKMeansExample”)
    .setMaster(“local[2]”)
    .set(“spark.executor.memory”,”3g”)
    .set(“spark.driver.memory”, “3g”);
• JavaSparkContext jsc = new JavaSparkContext(conf);
  <apache-installation-directory>/conf/spark-env.sh file, located locally on the machine, contains information regarding Spark Environment configuration.
• Spark Master is one the parameters that could be provided in the configuration file