# Resources
- [Mailing Lists](discussion.html)
- [Developer](developer.html)
- [Features](features.html)
- [Releases](downloads.html)
- [System Requirements](systemreqs.html)
# Release Docs
- [4.0](./4_0_0/index.html)
- [3.6.1](./3_6_1/index.html)
# About
- [License](http://www.apache.org/licenses/LICENSE-2.0)
- [Who We are](../whoweare.html)
# ASF links
- [Apache Software Foundation](http://www.apache.org)
- [Thanks](http://www.apache.org/foundation/thanks.html)
- [Become a Sponsor](http://www.apache.org/foundation/sponsorship.html)
# Related Projects
- [Apache Hadoop](http://hadoop.apache.org)
- [Apache ManifoldCF](http://manifoldcf.apache.org/)
- [Apache Lucene.Net](http://lucenenet.apache.org/)
- [Apache Lucy](http://lucy.apache.org/)
- [Apache Mahout](http://mahout.apache.org)
- [Apache Nutch](http://nutch.apache.org)
- [Apache OpenNLP](http://opennlp.apache.org/)
- [Apache Tika](http://tika.apache.org)
- [Apache Zookeeper](http://zookeeper.apache.org)