diff --git a/bbb.go b/bbb.go
index aba077d..f0c87f0 100644
--- a/bbb.go
+++ b/bbb.go
@@ -1,3 +1,10 @@
+// BeagleBone Black support.
+// The following features are supported on Linux kernel 3.8+
+//
+//	GPIO (both digital (rw) and analog (ro))
+//	I2C
+//	LED
+
 package embd
 
 import (
diff --git a/descriptor.go b/descriptor.go
index 5f1117a..2d161b9 100644
--- a/descriptor.go
+++ b/descriptor.go
@@ -1,3 +1,5 @@
+// Host descriptor data structures.
+
 package embd
 
 import (
@@ -5,16 +7,20 @@ import (
 	"fmt"
 )
 
+// Descriptor represents a host descriptor.
 type Descriptor struct {
 	GPIODriver func() GPIODriver
 	I2CDriver  func() I2CDriver
 	LEDDriver  func() LEDDriver
 }
 
+// The Describer type is a Descriptor provider.
 type Describer func(rev int) *Descriptor
 
+// Describers is a global list of registered host Describers.
 var Describers = map[Host]Describer{}
 
+// DescribeHost returns the detected host descriptor.
 func DescribeHost() (*Descriptor, error) {
 	host, rev, err := DetectHost()
 	if err != nil {
@@ -29,5 +35,10 @@ func DescribeHost() (*Descriptor, error) {
 	return describer(rev), nil
 }
 
+// ErrFeatureNotSupported is returned when the host does not support a
+// particular feature.
 var ErrFeatureNotSupported = errors.New("embd: requested feature is not supported")
+
+// ErrFeatureNotImplemented is returned when a particular feature is supported
+// by the host but not implemented yet.
 var ErrFeatureNotImplemented = errors.New("embd: requested feature is not implemented")
diff --git a/detect.go b/detect.go
index e1c1acc..24d045b 100644
--- a/detect.go
+++ b/detect.go
@@ -1,3 +1,5 @@
+// Host detection.
+
 package embd
 
 import (
@@ -7,13 +9,23 @@ import (
 	"strings"
 )
 
+// The Host type represents all the supported host types.
 type Host int
 
 const (
+	// HostNull reprents a null host.
 	HostNull Host = iota
+
+	// HostRPi represents the RaspberryPi.
 	HostRPi
+
+	// HostBBB represents the BeagleBone Black.
 	HostBBB
+
+	// HostCubieTruck represents the Cubie Truck.
 	HostCubieTruck
+
+	// HostGalileo represents the Intel Galileo board.
 	HostGalileo
 )
 
@@ -60,6 +72,7 @@ func kernelVersion() (major, minor, patch int, err error) {
 	return parseVersion(output)
 }
 
+// DetectHost returns the detected host and its revision number.
 func DetectHost() (Host, int, error) {
 	major, minor, patch, err := kernelVersion()
 	if err != nil {
diff --git a/i2c.go b/i2c.go
index fd65e8f..152cf96 100644
--- a/i2c.go
+++ b/i2c.go
@@ -1,5 +1,8 @@
+// I2C support.
+
 package embd
 
+// I2CBus interface is used to interact with the I2C bus.
 type I2CBus interface {
 	// ReadByte reads a byte from the given address.
 	ReadByte(addr byte) (value byte, err error)
@@ -23,6 +26,8 @@ type I2CBus interface {
 	WriteWordToReg(addr, reg byte, value uint16) error
 }
 
+// I2CDriver interface interacts with the host descriptors to allow us
+// control of I2C communication.
 type I2CDriver interface {
 	Bus(l byte) I2CBus
 
@@ -31,6 +36,7 @@ type I2CDriver interface {
 
 var i2cDriverInstance I2CDriver
 
+// InitI2C initializes the I2C driver.
 func InitI2C() error {
 	desc, err := DescribeHost()
 	if err != nil {
@@ -46,10 +52,12 @@ func InitI2C() error {
 	return nil
 }
 
+// CloseI2C gracefully closes the I2C driver.
 func CloseI2C() error {
 	return i2cDriverInstance.Close()
 }
 
+// NewI2CBus returns a I2CBus corresponding to the provided address.
 func NewI2CBus(l byte) I2CBus {
 	return i2cDriverInstance.Bus(l)
 }
diff --git a/led.go b/led.go
index ec7897a..bb222f6 100644
--- a/led.go
+++ b/led.go
@@ -1,5 +1,8 @@
+// LED support.
+
 package embd
 
+// The LED interface is used to control a led on the prototyping board.
 type LED interface {
 	On() error
 	Off() error
@@ -9,6 +12,8 @@ type LED interface {
 	Close() error
 }
 
+// LEDDriver interface interacts with the host descriptors to allow us
+// control of the LEDs.
 type LEDDriver interface {
 	LED(key interface{}) (LED, error)
 
@@ -17,6 +22,7 @@ type LEDDriver interface {
 
 var ledDriverInstance LEDDriver
 
+// InitLED initializes the LED driver.
 func InitLED() error {
 	desc, err := DescribeHost()
 	if err != nil {
@@ -32,14 +38,18 @@ func InitLED() error {
 	return nil
 }
 
+// CloseLED gracefully closes the LED driver.
 func CloseLED() error {
 	return ledDriverInstance.Close()
 }
 
+// NewLED returns a LED interface which allows control over the LED
+// represented by key.
 func NewLED(key interface{}) (LED, error) {
 	return ledDriverInstance.LED(key)
 }
 
+// LEDOn switches the corresponding LED on.
 func LEDOn(key interface{}) error {
 	led, err := NewLED(key)
 	if err != nil {
@@ -49,6 +59,7 @@ func LEDOn(key interface{}) error {
 	return led.On()
 }
 
+// LEDOff switches the corresponding LED off.
 func LEDOff(key interface{}) error {
 	led, err := NewLED(key)
 	if err != nil {
@@ -58,6 +69,7 @@ func LEDOff(key interface{}) error {
 	return led.Off()
 }
 
+// LEDToggle toggles the corresponding LED.
 func LEDToggle(key interface{}) error {
 	led, err := NewLED(key)
 	if err != nil {
diff --git a/rpi.go b/rpi.go
index 7be216b..085572a 100644
--- a/rpi.go
+++ b/rpi.go
@@ -1,3 +1,9 @@
+// RaspberryPi support.
+// The following features are supported on Linux kernel 3.8+
+//
+//	GPIO (digital (rw))
+//	I2C
+
 package embd
 
 func init() {