diff --git a/.gitignore b/.gitignore
index c7eea7f..0c4e8bf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,9 @@
 ### MacOs ###
 .DS_Store
 
+### PhpStorm ###
+/.idea
+
 ### Composer ###
 composer.lock
 composer.phar
diff --git a/composer.json b/composer.json
index 2a3bd38..b399ba6 100644
--- a/composer.json
+++ b/composer.json
@@ -3,7 +3,8 @@
         "files": [ "src/classnames/function.php" ],
         "psr-4": {
             "ClassNames\\": "src/classnames",
-            "MergeCoverage\\": "src/merge-coverage"
+            "MergeCoverage\\": "src/merge-coverage",
+            "TimeOfDay\\": "src/time-of-day"
         }
     },
     "require-dev": {
diff --git a/phpunit.xml b/phpunit.xml
index 8e37f4a..eccb588 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -13,6 +13,9 @@
         <testsuite name="classnames">
             <directory>src/classnames/Tests</directory>
         </testsuite>
+        <testsuite name="time-of-day">
+            <directory>src/time-of-day/Tests</directory>
+        </testsuite>
     </testsuites>
 
     <source restrictDeprecations="true" restrictNotices="true" restrictWarnings="true">
diff --git a/src/time-of-day/AbstractTime.php b/src/time-of-day/AbstractTime.php
new file mode 100644
index 0000000..ed4ca54
--- /dev/null
+++ b/src/time-of-day/AbstractTime.php
@@ -0,0 +1,56 @@
+<?php
+
+namespace TimeOfDay;
+
+abstract class AbstractTime
+{
+    const MILLISECONDS_IN_A_DAY = 24 * 60 * 60 * 1000;
+    const MILLISECONDS_IN_A_HOUR = 60 * 60 * 1000;
+    const MILLISECONDS_IN_A_MINUTE = 60 * 1000;
+
+    protected int $counter;
+
+    public static function fromParts(
+        int $hours,
+        ?int $minutes = 0,
+        ?int $seconds = 0,
+        ?int $milliseconds = 0
+    ) {
+        match(true) {
+            (0 > $hours || $hours > 23)  => throw new \ValueError('Hour is not valid'),
+            (0 > $minutes || $minutes > 59) => throw new \ValueError('Minute is not valid'),
+            (0 > $seconds || $seconds > 59)  => throw new \ValueError('Second is not valid'),
+            (0 > $milliseconds || $milliseconds > 999) => throw new \ValueError('Millisecond is not valid'),
+            default => 'Everything is ok'
+        };
+
+        return new static(
+            $hours * self::MILLISECONDS_IN_A_HOUR
+            + $minutes * self::MILLISECONDS_IN_A_MINUTE
+            + $seconds * 1000
+            + $milliseconds
+        );
+    }
+
+    protected function hours(): int
+    {
+        return intdiv($this->counter, self::MILLISECONDS_IN_A_HOUR);
+    }
+
+    protected function minutes(): int
+    {
+        $rest = $this->counter % self::MILLISECONDS_IN_A_HOUR;
+        return intdiv($rest, self::MILLISECONDS_IN_A_MINUTE);
+    }
+    
+    protected function seconds(): int
+    {
+        $rest = $this->counter % self::MILLISECONDS_IN_A_MINUTE;
+        return intdiv($rest, 1000);
+    }
+    
+    protected function milliseconds(): int
+    {
+        return $this->counter % 1000;
+    }
+}
\ No newline at end of file
diff --git a/src/time-of-day/Duration.php b/src/time-of-day/Duration.php
new file mode 100644
index 0000000..840267e
--- /dev/null
+++ b/src/time-of-day/Duration.php
@@ -0,0 +1,29 @@
+<?php
+
+namespace TimeOfDay;
+
+class Duration extends AbstractTime
+{
+    public function __construct(int $counter)
+    {
+        if (0 > $counter) {
+            throw new \ValueError('Milliseconds should be a positive integer');
+        }
+        $this->counter = $counter;
+    }
+    
+    public function equals(Duration $other): bool
+    {
+        return $this->counter === $other->counter;
+    }
+    
+    public function isGreater(Duration $other): bool
+    {
+        return $this->counter > $other->counter;
+    }
+    
+    public function isLess(Duration $other): bool
+    {
+        return $this->counter < $other->counter;
+    }
+}
\ No newline at end of file
diff --git a/src/time-of-day/Tests/DurationTest.php b/src/time-of-day/Tests/DurationTest.php
new file mode 100644
index 0000000..bad994a
--- /dev/null
+++ b/src/time-of-day/Tests/DurationTest.php
@@ -0,0 +1,93 @@
+<?php
+declare(strict_types=1);
+
+namespace TimeOfDay\Tests;
+
+use PHPUnit\Framework\TestCase;
+use PHPUnit\Framework\Attributes\Test;
+use TimeOfDay\Duration;
+use TimeOfDay\TimeOfDay;
+
+class DurationTest extends TestCase
+{
+    #[Test]
+    public function fromParts(): void
+    {
+        $result = Duration::fromParts(12);
+        $expected = new Duration(12 * 60 * 60 * 1000);
+        self::assertEquals($expected, $result);
+
+        $result = Duration::fromParts(12,34);
+        $expected = new Duration(12 * 60 * 60 * 1000 + 34 * 60 * 1000);
+        self::assertEquals($expected, $result);
+
+        $result = Duration::fromParts(12, 34 , 56 );
+        $expected = new Duration(12 * 60 * 60 * 1000 + 34 * 60 * 1000 + 56 * 1000);
+        self::assertEquals($expected, $result);
+
+        $result = Duration::fromParts(0);
+        $expected = new Duration(0);
+        self::assertEquals($expected, $result);
+    }
+
+    #[Test]
+    public function hourNotValidTooBig(): void
+    {
+        self::expectException(\ValueError::class);
+        self::expectExceptionMessage('Hour is not valid');
+        Duration::fromParts(24);
+    }
+    
+    #[Test]
+    public function hourNotValidTooSmall(): void
+    {
+        self::expectException(\ValueError::class);
+        self::expectExceptionMessage('Hour is not valid');
+        TimeOfDay::fromParts(-3);
+    }
+    
+    #[Test]
+    public function minuteNotValid(): void
+    {
+        self::expectException(\ValueError::class);
+        self::expectExceptionMessage('Minute is not valid');
+        TimeOfDay::fromParts(12, 60);
+    }
+    
+    #[Test]
+    public function secondNotValid(): void
+    {
+        self::expectException(\ValueError::class);
+        self::expectExceptionMessage('Second is not valid');
+        TimeOfDay::fromParts(12, 34 , 60);
+    }
+    
+    #[Test]
+    public function comparison(): void
+    {
+        $foo = Duration::fromParts(12, 34 , 56);
+        $bar = Duration::fromParts(12);
+
+        self::assertTrue($foo->isGreater($bar));
+        self::assertTrue($bar->isLess($foo));
+    }
+
+    #[Test]
+    public function equalsComparison(): void
+    {
+        $foo = Duration::fromParts(12, 34 , 0);
+        $bar = Duration::fromParts(12, 34);
+    
+        self::assertTrue($foo->equals($bar));
+    }
+
+    #[Test]
+    public function equalsComparisonBetweenChildrenObjects(): void
+    {
+        $foo = Duration::fromParts(12, 34 , 0);
+        $bar = TimeOfDay::fromParts(12, 34);
+
+        self::expectException(\TypeError::class);
+        self::assertTrue($foo->equals($bar));
+    }
+}
\ No newline at end of file
diff --git a/src/time-of-day/Tests/TimeOfDayTest.php b/src/time-of-day/Tests/TimeOfDayTest.php
new file mode 100644
index 0000000..d252933
--- /dev/null
+++ b/src/time-of-day/Tests/TimeOfDayTest.php
@@ -0,0 +1,140 @@
+<?php
+declare(strict_types=1);
+
+namespace TimeOfDay\Tests;
+
+use PHPUnit\Framework\TestCase;
+use PHPUnit\Framework\Attributes\Test;
+use TimeOfDay\TimeOfDay;
+use TimeOfDay\Duration;
+
+class TimeOfDayTest extends TestCase
+{
+    #[Test]
+    public function timeOfDay(): void
+    {
+        $result = new TimeOfDay(45296000);
+        $expected = new \DateTimeImmutable('2000-01-01 12:34:56');
+        
+        self::assertSame($expected->format('H:i:s'), $result->format('H:i:s'));
+    }
+
+    #[Test]
+    public function plop(): void
+    {
+        $time = new TimeOfDay(45296000);
+        $result = $time->onDay(new \DateTimeImmutable('2000-01-01'));
+    
+        $expected = new \DateTimeImmutable('2000-01-01 12:34:56');
+    
+        self::assertEquals($expected, $result);
+    }
+
+    #[Test]
+    public function negativeMilliseconds(): void
+    {
+        $result = new TimeOfDay(-45296000);
+        self::assertEquals(new TimeOfDay(41104000), $result);
+
+        $result = new TimeOfDay(-131696000);
+        self::assertEquals(new TimeOfDay(41104000), $result);
+    }
+
+    #[Test]
+    public function comparison(): void
+    {
+        $foo = TimeOfDay::fromParts(12, 34 , 56);
+        $bar = TimeOfDay::fromParts(12);
+
+        self::assertTrue($foo->isAfter($bar));
+        self::assertTrue($bar->isBefore($foo));
+    }
+    
+    #[Test]
+    public function equalsComparison(): void
+    {
+        $foo = TimeOfDay::fromParts(12, 34 , 0);
+        $bar = TimeOfDay::fromParts(12, 34);
+    
+        self::assertTrue($foo->equals($bar));
+    }
+    
+    #[Test]
+    public function fromParts(): void
+    {
+        $result = TimeOfDay::fromParts(12);
+        $expected = new TimeOfDay(12 * 60 * 60 * 1000);
+        self::assertEquals($expected, $result);
+
+        $result = TimeOfDay::fromParts(12,34);
+        $expected = new TimeOfDay(12 * 60 * 60 * 1000 + 34 * 60 * 1000);
+        self::assertEquals($expected, $result);
+
+        $result = TimeOfDay::fromParts(12, 34 , 56 );
+        $expected = new TimeOfDay(12 * 60 * 60 * 1000 + 34 * 60 * 1000 + 56 * 1000);
+        self::assertEquals($expected, $result);
+
+        $result = TimeOfDay::fromParts(0);
+        $expected = new TimeOfDay(0);
+        self::assertEquals($expected, $result);
+    }
+
+    #[Test]
+    public function hourNotValidTooBig(): void
+    {
+        self::expectException(\ValueError::class);
+        self::expectExceptionMessage('Hour is not valid');
+        TimeOfDay::fromParts(24);
+    }
+    
+    #[Test]
+    public function hourNotValidTooSmall(): void
+    {
+        self::expectException(\ValueError::class);
+        self::expectExceptionMessage('Hour is not valid');
+        TimeOfDay::fromParts(-3);
+    }
+
+    #[Test]
+    public function minuteNotValid(): void
+    {
+        self::expectException(\ValueError::class);
+        self::expectExceptionMessage('Minute is not valid');
+        TimeOfDay::fromParts(12, 60);
+    }
+
+    #[Test]
+    public function secondNotValid(): void
+    {
+        self::expectException(\ValueError::class);
+        self::expectExceptionMessage('Second is not valid');
+        TimeOfDay::fromParts(12, 34 , 60);
+    }
+    
+    #[Test]
+    public function passedSince(): void
+    {
+        $time = new TimeOfDay(45296000);
+        $duration = $time->passedSince(new TimeOfDay(44296000));
+        
+        self::assertEquals(new Duration(1000000), $duration);
+    }
+
+    #[Test]
+    public function was(): void
+    {
+        $time = new TimeOfDay(45296000);
+        $was = $time->was(new Duration(1000000));
+    
+        self::assertEquals(new TimeOfDay(44296000), $was);
+    }
+
+    #[Test]
+    public function willBe(): void
+    {
+        $time = new TimeOfDay(45296000);
+        $was = $time->willBe(new Duration(1000000));
+    
+        self::assertEquals(new TimeOfDay(46296000), $was);
+    }
+}
diff --git a/src/time-of-day/TimeOfDay.php b/src/time-of-day/TimeOfDay.php
new file mode 100644
index 0000000..3000365
--- /dev/null
+++ b/src/time-of-day/TimeOfDay.php
@@ -0,0 +1,57 @@
+<?php
+
+namespace TimeOfDay;
+
+class TimeOfDay extends AbstractTime
+{
+    public function __construct(int $milliseconds)
+    {
+        $rest = $milliseconds % self::MILLISECONDS_IN_A_DAY;
+        $this->counter = $rest + (0 > $rest ? self::MILLISECONDS_IN_A_DAY : 0);
+    }
+    
+    public function passedSince(TimeOfDay $other)
+    {
+        return new Duration($this->counter - $other->counter);
+    }
+    
+    public function was(Duration $duration): TimeOfDay
+    {
+        return new self($this->counter - $duration->counter);
+    }
+    
+    public function willBe(Duration $duration): TimeOfDay
+    {
+        return new self($this->counter + $duration->counter);
+    }
+    
+    public function equals(TimeOfDay $other): bool
+    {
+        return $this->counter === $other->counter;
+    }
+    
+    public function isBefore(TimeOfDay $other): bool
+    {
+        return $this->counter < $other->counter;
+    }
+
+    public function isAfter(TimeOfDay $other): bool
+    {
+        return $this->counter > $other->counter;
+    }
+
+    public function format(string $format): string
+    {
+        return $this->onDay(new \DateTimeImmutable())->format($format);
+    }
+    
+    public function onDay(\DateTimeImmutable $day): \DateTimeImmutable
+    {
+        return ($day)->setTime(
+            $this->hours(),
+            $this->minutes(),
+            $this->seconds(),
+            $this->milliseconds(),
+        );
+    }
+}
\ No newline at end of file