Jackson Core 
Package Description
org.codehaus.jackson
Main public API classes of the core streaming JSON processor: most importantly JsonFactory used for constructing JSON parser (JsonParser) and generator (JsonParser) instances.
org.codehaus.jackson.annotate
Public core annotations, most of which are used to configure how Data Mapping/Binding works.
org.codehaus.jackson.format
Package that contains interfaces needed for dynamic, pluggable format (auto)detection; as well as basic utility classes for simple format detection functionality.
org.codehaus.jackson.impl
Parser and generator implementation classes that Jackson defines and uses.
org.codehaus.jackson.io
This package contains I/O helper classes Jackson itself uses, but that are not exposed for external reuse.
org.codehaus.jackson.sym
Internal implementation classes for efficient handling of of symbols in JSON (field names in Objects)
org.codehaus.jackson.type
Contains classes needed for type introspection, mostly used by data binding functionality.
org.codehaus.jackson.util
Utility classes used by Jackson Core functionality.
Jackson Mapper 
Package Description
org.codehaus.jackson.map
Contains basic mapper (conversion) functionality that allows for converting between regular streaming json content and Java objects (beans or Tree Model: support for both is via ObjectMapper class, as well as convenience methods included in JsonParser
org.codehaus.jackson.map.annotate
Annotations that directly depend on Mapper classes (not just Jackson core) and are used for configuring Data Mapping functionality.
org.codehaus.jackson.map.deser
Contains implementation classes of deserialization part of data binding.
org.codehaus.jackson.map.deser.impl
Contains those implementation classes of deserialization part of data binding that are not considered part of public or semi-public interfaces.
org.codehaus.jackson.map.deser.std
Contains public standard implementations of abstraction that Jackson uses.
org.codehaus.jackson.map.exc  
org.codehaus.jackson.map.ext
Contains extended support for "external" packages: things that may or may not be present in runtime environment, but that are commonly enough used so that explicit support can be added.
org.codehaus.jackson.map.introspect
Functionality needed for Bean introspection, required for detecting accessors and mutators for Beans, as well as locating and handling method annotations.
org.codehaus.jackson.map.jsontype
Package that contains interfaces that define how to implement functionality for dynamically resolving type during deserialization.
org.codehaus.jackson.map.jsontype.impl
Package that contains standard implementations for TypeResolverBuilder and TypeIdResolver.
org.codehaus.jackson.map.module
Package that contains classes and interfaces to help implement custom extension Modules (which are registered using ObjectMapper.registerModule(org.codehaus.jackson.map.Module).
org.codehaus.jackson.map.ser
Contains implementation classes of serialization part of data binding.
org.codehaus.jackson.map.ser.impl
Contains implementation classes of serialization part of data binding.
org.codehaus.jackson.map.ser.std  
org.codehaus.jackson.map.type
Package that contains concrete implementations of JavaType, as well as the factory (TypeFactory) for constructing instances from various input data types (like Class, Type) and programmatically (for structured types, arrays, Lists and Maps).
org.codehaus.jackson.map.util
Utility classes for Mapper package.
org.codehaus.jackson.node
Contains concrete JsonNode implementations Jackson uses for the Tree model.
org.codehaus.jackson.schema
Classes needed for JSON schema support (currently just ability to generate schemas using serialization part of data mapping)
Jackson JAX-RS provider 
Package Description
org.codehaus.jackson.jaxrs
Jackson-based JAX-RS provider that can automatically serialize and deserialize resources for JSON content type (MediaType).
Jackson XML Compatibility 
Package Description
org.codehaus.jackson.xc
Package that contains XML Compatibility functionality for Jackson, such as handlers for JAXB annotations
Jackson Mr Bean 
Package Description
org.codehaus.jackson.mrbean
Package that implements "interface materializer" functionality, whereby abstract classes and interfaces can be used as-is, and framework constructs implementations as needed.
Jackson Smile Format 
Package Description
org.codehaus.jackson.smile
Package that contains experimental implementation of "Binary-Encoded JSON-Like" data format handlers (parser, generator, factory produce both, supporting constants).