<?php
$folder = "upload/";
if (is_uploaded_file($HTTP_POST_FILES['filename']['tmp_name']))  {
    if (move_uploaded_file($HTTP_POST_FILES['filename']['tmp_name'], $folder.$HTTP_POST_FILES['filename']['name'])) {
         echo "File uploaded";
    } else {
         echo "File not moved to destination folder. Check permissions";
    };
} else {s
     echo "File is not uploaded";
};
?>

<?php

 $target_dir = "upload/";
 $target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
 $uploadOk = 1;
 $imageFileType = pathinfo($target_file,PATHINFO_EXTENSION);

// Check if image file is a actual image or fake image
 if(isset($_POST["submit"])) {

    if ($target_file == "upload/") {
        $msg = "cannot be empty";
        $uploadOk = 0;
    }

// Check if file already exists
    else if (file_exists($target_file)) {
        $msg = "Sorry, file already exists.";
        $uploadOk = 0;
}

// Check file size
    else if ($_FILES["fileToUpload"]["size"] > 5000000) {
        $msg = "Sorry, your file is too large.";
        $uploadOk = 0;
}

// Check if $uploadOk is set to 0 by an error
    else if ($uploadOk == 0) {
        $msg = "Sorry, your file was not uploaded.";

// if everything is ok, try to upload file
}   else {

        if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) {
            $msg = "The file ". basename( $_FILES["fileToUpload"]["name"]). " has been uploaded.";
}

}

}

?>

<form action="upload.php" method="post" id="myForm" enctype="multipart/form-data">
    Select file to upload:
    <input type="file" name="fileToUpload" id="fileToUpload">
    <button name="submit" class="btn btn-primary" type="submit" value="submit">Upload File</button>
 </form>

public static function uploadFile($filepath="upload",$existCheck=0,$uniq=0){
   global $_FILES;
   try {
        // Undefined | Multiple Files | $_FILES Corruption Attack
        // If this request falls under any of them, treat it invalid.
        if (
            !isset($_FILES['uploaded_file']['error']) ||
            is_array($_FILES['uploaded_file']['error'])
        ) {
            $result["status"]="fail";$result["errors"]=('Invalid parameters.');return $result;
        }


        // Check $_FILES['uploaded_file']['error'] value.
        switch ($_FILES['uploaded_file']['error']) {
            case UPLOAD_ERR_OK:
                break;
            case UPLOAD_ERR_NO_FILE:
                $result["status"]="fail";$result["errors"]=('No file sent.');return $result;
            case UPLOAD_ERR_INI_SIZE:
            case UPLOAD_ERR_FORM_SIZE:
                $result["status"]="fail";$result["errors"]=('Exceeded filesize limit.');return $result;
            default:
                $result["status"]="fail";$result["errors"]=('Unknown errors.');return $result;
        }

        // You should also check filesize here.
        if ($_FILES['uploaded_file']['size'] > 1000000) {
            $result["status"]="fail";$result["errors"]=('Exceeded filesize limit.');return $result;
        }

        // DO NOT TRUST $_FILES['uploaded_file']['mime'] VALUE !!
        // Check MIME Type by yourself.
        $finfo = new finfo(FILEINFO_MIME_TYPE);
        if (false === $ext = array_search(
            $finfo->file($_FILES['uploaded_file']['tmp_name']),
            array(
                'jpg' => 'image/jpeg',
                'png' => 'image/png',
                'gif' => 'image/gif',
            ),
            true
        )) {
            $result["status"]="fail";$result["errors"]=('Invalid file format.');return $result;
        }
        if($uniq==0){
            $temp=$filepath;
        }
        else{
            $temp=$filepath."/".uniqid()."_".$_FILES['uploaded_file']['name'];
        }

        if ($existCheck==1 && file_exists($temp)) {
            $result["status"]="fail";$result["errors"]=('Unknown errors.');return $result;
        }
        if(@copy($_FILES['uploaded_file']['tmp_name'], $temp)) {
            return $result["status"]="success";
        }
        $result["status"]="fail";$result["errors"]=('Unknown errors.');return $result;

    } catch (Exception $e) {

            $result["status"]="fail";$result["errors"]= $e->getMessage();return $result;

    }
}

first, your write html code like this don't forget to write enctype="multipart/form-data"  and then crerte new file name is upload.php

<form action="upload.php" method="post" enctype="multipart/form-data">
  <input type="file" name="fileToUpload" id="fileToUpload">
  <input type="submit" value="Upload Image" name="submit">
</form>
  $path = "form/";
  $target_file =  $path.basename($_FILES["fileToUpload"]["name"]);
  $file=$_FILES['fileToUpload']['name'];
  $result = move_uploaded_file($_FILES['fileToUpload']['tmp_name'],$target_file.$file);
  if ($result) {
   echo "file successfully uploaded";
  }
  else {
    echo "please select your file";
   }