php artisan make:model Tag -m

php artisan make:migration create_note_tag_table --create=note_tag

Schema::create('note_tag', function (Blueprint $table) {
    $table->id();
    $table->foreignId('note_id')->constrained()->onDelete('cascade');
    $table->foreignId('tag_id')->constrained()->onDelete('cascade');
    $table->timestamps();
});

Schema::create('tags', function (Blueprint $table) {
    $table->id();
    $table->string('name')->unique();
    $table->timestamps();
});

php artisan migrate

    public function tags()
    {
        return $this->belongsToMany(Tag::class);
    }

class Tag extends Model
{
    protected $fillable = ['name'];

    public function notes()
    {
        return $this->belongsToMany(Note::class);
    }
}

<input type="text" id="tags" name="tags" class="bg-gray-50 border border-gray-300 text-gray-900 text-sm rounded-lg focus:ring-blue-500 focus:border-blue-500 block w-full p-2.5" placeholder="Tags, sepeate using comma.">

    public function store(Request $request)
    {
        $data = $request->validate([
            'title' => ['required', 'string'],
            'note' => ['required', 'string'],
            'tags' => 'nullable|string'
        ]);

        $user = Auth::user();

        $note = $user->notes()->create([
            'title' => $data['title'],
            'note' => $data['note'],
        ]);

        // Process the tags if any are provided
        if (!empty($data['tags'])) {
            // Split the tags string into an array
            $tagNames = explode(',', $data['tags']);

            // Trim whitespace and create/find each tag
            $tagIds = [];
            foreach ($tagNames as $tagName) {
                $tag = Tag::firstOrCreate(['name' => trim($tagName)]);
                $tagIds[] = $tag->id;
            }

            // Attach the tags to the note
            $note->tags()->attach($tagIds);
        }

        <h4>Tags:</h4>
        @if($note->tags->isEmpty())
            <p>No tags associated with this note.</p>
        @else
            <ul>
                @foreach($note->tags as $tag)
                    <li>{{ $tag->name }}</li>
                @endforeach
            </ul>
        @endif

Route::middleware(["auth","verified"])->group(function () {
    Route::resource('note', NoteController::class);
});

<nav>
    <ul>
        <!-- Other navigation links -->

        @auth
            <!-- User is logged in -->
            <li><a href="{{ route('profile') }}">Profile</a></li>
            <li><a href="{{ route('logout') }}" onclick="event.preventDefault(); document.getElementById('logout-form').submit();">Logout</a></li>
            
            <form id="logout-form" action="{{ route('logout') }}" method="POST" style="display: none;">
                @csrf
            </form>
        @else
            <!-- User is not logged in -->
            <li><a href="{{ route('login') }}">Login</a></li>
            <li><a href="{{ route('register') }}">Register</a></li>
        @endauth
    </ul>
</nav>