# All Packages

- Package Summary
  Package | Description
  --- | ---
  org.apache.lucene.analysis | Text analysis.
  org.apache.lucene.analysis.standard | Fast, general-purpose grammar-based tokenizer `StandardTokenizer` implements the Word Break rules from the Unicode Text Segmentation algorithm, as specified in Unicode Standard Annex #29.
  org.apache.lucene.analysis.tokenattributes | General-purpose attributes for text analysis.
  org.apache.lucene.codecs | Codecs API: API for customization of the encoding and structure of the index.
  org.apache.lucene.codecs.compressing | Compressing helper classes.
  org.apache.lucene.codecs.lucene90 | Lucene 9.0 file format.
  org.apache.lucene.codecs.lucene90.blocktree | BlockTree terms dictionary.
  org.apache.lucene.codecs.lucene90.compressing | Lucene 9.0 compressing format.
  org.apache.lucene.codecs.lucene94 | Lucene 9.4 file format.
  org.apache.lucene.codecs.lucene95 | Lucene 9.5 file format.
  org.apache.lucene.codecs.lucene99 | Lucene 9.9 file format.
  org.apache.lucene.codecs.perfield | Postings format that can delegate to different formats per-field.
  org.apache.lucene.document | The logical representation of a `Document` for indexing and searching.
  org.apache.lucene.geo | Geospatial Utility Implementations for Lucene Core
  org.apache.lucene.index | Code to maintain and access indices.
  org.apache.lucene.internal.tests | Internal bridges to package-private internals, for use by the lucene test framework only.
  org.apache.lucene.internal.vectorization | Internal implementations to support SIMD vectorization.
  org.apache.lucene.search | Code to search indices.
  org.apache.lucene.search.comparators | Comparators, used to compare hits so as to determine their sort order when collecting the top results with `TopFieldCollector`.
  org.apache.lucene.search.knn | Classes related to vector search: knn and vector fields.
  org.apache.lucene.search.similarities | This package contains the various ranking models that can be used in Lucene.
  org.apache.lucene.store | Binary i/o API, used for all index data.
  org.apache.lucene.util | Some utility classes.
  org.apache.lucene.util.automaton | Finite-state automaton for regular expressions.
  org.apache.lucene.util.bkd | Block KD-tree, implementing the generic spatial data structure described in this paper.
  org.apache.lucene.util.compress | Compression utilities.
  org.apache.lucene.util.fst | Finite state transducers
  org.apache.lucene.util.graph | Utility classes for working with token streams as graphs.
  org.apache.lucene.util.hnsw | Navigable Small-World graph, nominally Hierarchical but currently only has a single layer.
  org.apache.lucene.util.hppc | package holding hppc related classes.
  org.apache.lucene.util.mutable | Comparable object wrappers
  org.apache.lucene.util.packed | Packed integer arrays and streams.
  org.apache.lucene.util.quantization | Provides quantization methods for scaling vector values to smaller data types and possibly fewer dimensions