diff --git a/src/types/Array.go b/src/types/Array.go
new file mode 100644
index 0000000..75e5f13
--- /dev/null
+++ b/src/types/Array.go
@@ -0,0 +1,16 @@
+package types
+
+// Array is the address of an object.
+type Array struct {
+	Of Type
+}
+
+// Name returns the type name.
+func (a *Array) Name() string {
+	return "[]" + a.Of.Name()
+}
+
+// Size returns the total size in bytes.
+func (a *Array) Size() int {
+	return 8
+}
\ No newline at end of file
diff --git a/src/types/Base.go b/src/types/Base.go
new file mode 100644
index 0000000..520e318
--- /dev/null
+++ b/src/types/Base.go
@@ -0,0 +1,17 @@
+package types
+
+// Base is used to describe basic types like integers and floats.
+type Base struct {
+	name string
+	size int
+}
+
+// Name returns the name of the type.
+func (s *Base) Name() string {
+	return s.name
+}
+
+// Size returns the total size in bytes.
+func (s *Base) Size() int {
+	return s.size
+}
\ No newline at end of file
diff --git a/src/types/Common.go b/src/types/Common.go
new file mode 100644
index 0000000..6af5a2f
--- /dev/null
+++ b/src/types/Common.go
@@ -0,0 +1,27 @@
+package types
+
+var (
+	Any        = &Base{name: "any", size: 0}
+	AnyArray   = &Array{Of: Any}
+	AnyInt     = &Base{name: "int"}
+	AnyPointer = &Pointer{To: Any}
+	Bool       = &Base{name: "bool", size: 1}
+	Int64      = &Base{name: "int64", size: 8}
+	Int32      = &Base{name: "int32", size: 4}
+	Int16      = &Base{name: "int16", size: 2}
+	Int8       = &Base{name: "int8", size: 1}
+	Float64    = &Base{name: "float64", size: 8}
+	Float32    = &Base{name: "float32", size: 4}
+	String     = &Array{Of: Byte}
+	UInt64     = &Base{name: "uint64", size: 8}
+	UInt32     = &Base{name: "uint32", size: 4}
+	UInt16     = &Base{name: "uint16", size: 2}
+	UInt8      = &Base{name: "uint8", size: 1}
+)
+
+var (
+	Byte  = UInt8
+	Float = Float64
+	Int   = Int64
+	UInt  = UInt64
+)
\ No newline at end of file
diff --git a/src/types/Is.go b/src/types/Is.go
new file mode 100644
index 0000000..3a54a64
--- /dev/null
+++ b/src/types/Is.go
@@ -0,0 +1,47 @@
+package types
+
+// Is returns true if the encountered type `a` can be converted into the expected type `b`.
+func Is(a Type, b Type) bool {
+	if a == b || b == Any || a == nil {
+		return true
+	}
+
+	aPointer, aIsPointer := a.(*Pointer)
+	bPointer, bIsPointer := b.(*Pointer)
+
+	if aIsPointer && bIsPointer && (bPointer.To == Any || aPointer.To == bPointer.To) {
+		return true
+	}
+
+	aArray, aIsArray := a.(*Array)
+
+	if aIsArray && bIsPointer && (bPointer.To == Any || aArray.Of == bPointer.To) {
+		return true
+	}
+
+	bArray, bIsArray := b.(*Array)
+
+	if aIsArray && bIsArray && (bArray.Of == Any || aArray.Of == bArray.Of) {
+		return true
+	}
+
+	if a == AnyInt {
+		switch b {
+		case Int64, Int32, Int16, Int8, UInt64, UInt32, UInt16, UInt8, AnyInt:
+			return true
+		default:
+			return false
+		}
+	}
+
+	if b == AnyInt {
+		switch a {
+		case Int64, Int32, Int16, Int8, UInt64, UInt32, UInt16, UInt8, AnyInt:
+			return true
+		default:
+			return false
+		}
+	}
+
+	return false
+}
\ No newline at end of file
diff --git a/src/types/Pointer.go b/src/types/Pointer.go
new file mode 100644
index 0000000..c836613
--- /dev/null
+++ b/src/types/Pointer.go
@@ -0,0 +1,16 @@
+package types
+
+// Pointer is the address of an object.
+type Pointer struct {
+	To Type
+}
+
+// Name returns the type name.
+func (p *Pointer) Name() string {
+	return "*" + p.To.Name()
+}
+
+// Size returns the total size in bytes.
+func (p *Pointer) Size() int {
+	return 8
+}
\ No newline at end of file
diff --git a/src/types/Type.go b/src/types/Type.go
index 4d6d132..c2e24c0 100644
--- a/src/types/Type.go
+++ b/src/types/Type.go
@@ -1,3 +1,7 @@
 package types
 
-type Type interface{}
\ No newline at end of file
+// Type is the generic interface for different data types.
+type Type interface {
+	Name() string
+	Size() int
+}
\ No newline at end of file
diff --git a/src/types/types_test.go b/src/types/types_test.go
new file mode 100644
index 0000000..769a24b
--- /dev/null
+++ b/src/types/types_test.go
@@ -0,0 +1,61 @@
+package types_test
+
+import (
+	"testing"
+
+	"git.urbach.dev/cli/q/src/types"
+	"git.urbach.dev/go/assert"
+)
+
+func TestName(t *testing.T) {
+	assert.Equal(t, types.Int.Name(), "int64")
+	assert.Equal(t, types.AnyArray.Name(), "[]any")
+	assert.Equal(t, types.AnyPointer.Name(), "*any")
+	assert.Equal(t, (&types.Pointer{To: types.Int}).Name(), "*int64")
+	assert.Equal(t, (&types.Array{Of: types.Int}).Name(), "[]int64")
+	assert.Equal(t, types.String.Name(), "[]uint8")
+}
+
+func TestSize(t *testing.T) {
+	assert.Equal(t, types.Int.Size(), 8)
+	assert.Equal(t, types.Int8.Size(), 1)
+	assert.Equal(t, types.Int16.Size(), 2)
+	assert.Equal(t, types.Int32.Size(), 4)
+	assert.Equal(t, types.Int64.Size(), 8)
+	assert.Equal(t, types.AnyArray.Size(), 8)
+	assert.Equal(t, types.AnyPointer.Size(), 8)
+	assert.Equal(t, types.String.Size(), 8)
+	assert.Equal(t, (&types.Pointer{To: types.Int}).Size(), 8)
+}
+
+func TestBasics(t *testing.T) {
+	assert.True(t, types.Is(types.Int, types.Int))
+	assert.True(t, types.Is(types.Int, types.Any))
+	assert.True(t, types.Is(types.Int, types.AnyInt))
+	assert.True(t, types.Is(types.AnyInt, types.AnyInt))
+	assert.True(t, types.Is(types.AnyInt, types.Int))
+	assert.True(t, types.Is(types.AnyPointer, types.AnyPointer))
+	assert.True(t, types.Is(&types.Array{Of: types.Int}, types.AnyArray))
+	assert.False(t, types.Is(types.Int, types.Float))
+	assert.False(t, types.Is(types.Any, types.Int))
+	assert.False(t, types.Is(types.AnyPointer, types.AnyInt))
+	assert.False(t, types.Is(types.AnyInt, types.AnyPointer))
+	assert.False(t, types.Is(&types.Pointer{To: types.Int}, &types.Pointer{To: types.Float}))
+}
+
+func TestSpecialCases(t *testing.T) {
+	// Case #1:
+	// For syscalls whose return type is `nil` we currently allow casting them to anything.
+	assert.True(t, types.Is(nil, types.Int))
+	assert.True(t, types.Is(nil, types.Float))
+
+	// Case #2:
+	// A pointer pointing to a known type fulfills the requirement of a pointer to anything.
+	assert.True(t, types.Is(&types.Pointer{To: types.Int}, types.AnyPointer))
+	assert.True(t, types.Is(&types.Pointer{To: types.Float}, types.AnyPointer))
+
+	// Case #3:
+	// Arrays are also just pointers.
+	assert.True(t, types.Is(&types.Array{Of: types.Int}, types.AnyPointer))
+	assert.True(t, types.Is(&types.Array{Of: types.Float}, types.AnyPointer))
+}
\ No newline at end of file