title: What does "pre-built for Apache Hadoop 2.7 and later" mean?
body: <p>What does "pre-built for Apache Hadoop 2.7 and later" mean on the download page of Apache Spark?</p>
  
  <p>Does it mean necessary libraries for HDFS in spark? If so, how about other storage systems like Cassandra, s3, HBase, SQL Databases, NoSQL databases?  Do we need to download any libraries to connect to other storage systems.</p>