diff --git a/wpilibc/src/main/native/include/frc/counter/ExternalDirectionCounter.h b/wpilibc/src/main/native/include/frc/counter/ExternalDirectionCounter.h
index 3591fa26b0..4d9faf2101 100644
--- a/wpilibc/src/main/native/include/frc/counter/ExternalDirectionCounter.h
+++ b/wpilibc/src/main/native/include/frc/counter/ExternalDirectionCounter.h
@@ -15,7 +15,12 @@
 namespace frc {
 class DigitalSource;
 
-/** Counter using external direction. */
+/** Counter using external direction.
+ *
+ * <p>This counts on an edge from one digital input and the whether it counts
+ * up or down based on the state of a second digital input.
+ *
+ */
 class ExternalDirectionCounter
     : public wpi::Sendable,
       public wpi::SendableHelper<ExternalDirectionCounter> {
@@ -51,7 +56,7 @@ class ExternalDirectionCounter
   int GetCount() const;
 
   /**
-   * Sets to revert the counter direction.
+   * Sets to reverse the counter direction.
    *
    * @param reverseDirection True to reverse counting direction.
    */
diff --git a/wpilibc/src/main/native/include/frc/counter/Tachometer.h b/wpilibc/src/main/native/include/frc/counter/Tachometer.h
index 6836a789c7..fb6e9e04ec 100644
--- a/wpilibc/src/main/native/include/frc/counter/Tachometer.h
+++ b/wpilibc/src/main/native/include/frc/counter/Tachometer.h
@@ -18,6 +18,12 @@ class DigitalSource;
 
 /**
  * Tachometer for getting rotational speed from a device.
+ *
+ * <p>The Tachometer class measures the time between digital pulses to
+ * determine the rotation speed of a mechanism. Examples of devices that could
+ * be used with the tachometer class are a hall effect sensor, break beam
+ * sensor, or optical sensor detecting tape on a shooter wheel. Unlike
+ * encoders, this class only needs a single digital input.
  */
 class Tachometer : public wpi::Sendable,
                    public wpi::SendableHelper<Tachometer> {
diff --git a/wpilibc/src/main/native/include/frc/counter/UpDownCounter.h b/wpilibc/src/main/native/include/frc/counter/UpDownCounter.h
index 71d92ce4d2..b01ce42642 100644
--- a/wpilibc/src/main/native/include/frc/counter/UpDownCounter.h
+++ b/wpilibc/src/main/native/include/frc/counter/UpDownCounter.h
@@ -15,7 +15,12 @@
 namespace frc {
 class DigitalSource;
 
-/** Up Down Counter. */
+/** Up Down Counter.
+ *
+ * This class can count edges on a single digital input or count up based on an
+ * edge from one digital input and down on an edge from another digital input.
+ *
+ */
 class UpDownCounter : public wpi::Sendable,
                       public wpi::SendableHelper<UpDownCounter> {
  public:
diff --git a/wpilibj/src/main/java/edu/wpi/first/wpilibj/counter/ExternalDirectionCounter.java b/wpilibj/src/main/java/edu/wpi/first/wpilibj/counter/ExternalDirectionCounter.java
index c09fd6f9c1..e10274b98d 100644
--- a/wpilibj/src/main/java/edu/wpi/first/wpilibj/counter/ExternalDirectionCounter.java
+++ b/wpilibj/src/main/java/edu/wpi/first/wpilibj/counter/ExternalDirectionCounter.java
@@ -16,7 +16,12 @@ import edu.wpi.first.wpilibj.DigitalSource;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 
-/** Counter using external direction. */
+/**
+ * Counter using external direction.
+ *
+ * <p>This counts on an edge from one digital input and the whether it counts up or down based on
+ * the state of a second digital input.
+ */
 public class ExternalDirectionCounter implements Sendable, AutoCloseable {
   private final DigitalSource m_countSource;
   private final DigitalSource m_directionSource;
@@ -67,7 +72,7 @@ public class ExternalDirectionCounter implements Sendable, AutoCloseable {
   }
 
   /**
-   * Sets to revert the counter direction.
+   * Sets to revese the counter direction.
    *
    * @param reverseDirection True to reverse counting direction.
    */
diff --git a/wpilibj/src/main/java/edu/wpi/first/wpilibj/counter/Tachometer.java b/wpilibj/src/main/java/edu/wpi/first/wpilibj/counter/Tachometer.java
index 037b28ecd0..834c153bd7 100644
--- a/wpilibj/src/main/java/edu/wpi/first/wpilibj/counter/Tachometer.java
+++ b/wpilibj/src/main/java/edu/wpi/first/wpilibj/counter/Tachometer.java
@@ -16,7 +16,14 @@ import edu.wpi.first.wpilibj.DigitalSource;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 
-/** Tachometer. */
+/**
+ * Tachometer.
+ *
+ * <p>The Tachometer class measures the time between digital pulses to determine the rotation speed
+ * of a mechanism. Examples of devices that could be used with the tachometer class are a hall
+ * effect sensor, break beam sensor, or optical sensor detecting tape on a shooter wheel. Unlike
+ * encoders, this class only needs a single digital input.
+ */
 public class Tachometer implements Sendable, AutoCloseable {
   private final DigitalSource m_source;
   private final int m_handle;
@@ -25,7 +32,7 @@ public class Tachometer implements Sendable, AutoCloseable {
   /**
    * Constructs a new tachometer.
    *
-   * @param source The source.
+   * @param source The DigitalSource (e.g. DigitalInput) of the Tachometer.
    */
   public Tachometer(DigitalSource source) {
     m_source = requireNonNullParam(source, "source", "Tachometer");
diff --git a/wpilibj/src/main/java/edu/wpi/first/wpilibj/counter/UpDownCounter.java b/wpilibj/src/main/java/edu/wpi/first/wpilibj/counter/UpDownCounter.java
index 0d3e341136..81d504e032 100644
--- a/wpilibj/src/main/java/edu/wpi/first/wpilibj/counter/UpDownCounter.java
+++ b/wpilibj/src/main/java/edu/wpi/first/wpilibj/counter/UpDownCounter.java
@@ -14,7 +14,12 @@ import edu.wpi.first.wpilibj.DigitalSource;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 
-/** Up Down Counter. */
+/**
+ * Up Down Counter.
+ *
+ * <p>This class can count edges on a single digital input or count up based on an edge from one
+ * digital input and down on an edge from another digital input.
+ */
 public class UpDownCounter implements Sendable, AutoCloseable {
   private DigitalSource m_upSource;
   private DigitalSource m_downSource;
@@ -88,7 +93,7 @@ public class UpDownCounter implements Sendable, AutoCloseable {
   }
 
   /**
-   * Sets to revert the counter direction.
+   * Sets to reverse the counter direction.
    *
    * @param reverseDirection True to reverse counting direction.
    */