For many Apache is synonymous to the Apache HTTP server, which is the backbone for serving the web pages. But, there is much more to Apache. It’s a non profit organization (ASF – Apache Software Foundation) which provides an environment and a platform in which different companies and individuals work in an open and collaborative fashion towards a common goal of developing a good piece of software. Open means that all the work (architecture, design, coding, testing, documentation etc) happens in an open way and there are no secrets. Anyone can also download the code, make some changes, compile it and push it back.
It’s possible for different companies and individuals like you and me to improve the code and contribute it back to the ASF. To maintain the quality of the software there is a process in place where the project committer will check the quality of the code contributed by someone and then add them to the code repository. The advantage of working in this model is that any improvements made by an individual or a company can be immediately absorbed by someone else. This is what working in a collaborative fashion means.
There are a lot of Big Data projects under the ASF like Hadoop, Hive, Pig, HBase, Cassandra and a lot of non Big Data projects like Tomcat, Log4J, Velocity, Struts. The projects usually start with Incubator status and then some of them move to the TLP status (Top Level Project). The code for the different projects can be accessed in a read only way from asf-revision 1769096.