Android : How to display data entered in one activity in another activity in list one by one in android?

FirstActivity.java

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    etName = (EditText) findViewById(R.id.etName);
    btnOk = (Button) findViewById(R.id.btnOk);

    btnOk.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {

            Name = etName.getText().toString();
            Intent intent = new Intent(getApplicationContext(),
                    SecondActivity.class);
            // Create a bundle object
            intent.putExtra("NAME", Name);

            startActivity(intent);
        }
    });

My second Activity.java



ArrayList<String> list = new ArrayList<String>();
ArrayAdapter<String> adapter;
String UName;
String iName;
ListView lvName;
Button btnBack;

Bundle savedInstanceState;

@Override
protected void onCreate(Bundle b) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.listview);

    b = getIntent().getExtras();
    lvName = (ListView) findViewById(R.id.lvNames);
    btnBack = (Button) findViewById(R.id.btnBack);

    adapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, list);


    UName=b.getString("NAME");


    list.add(UName);
    adapter.notifyDataSetChanged();
    lvName.setAdapter(adapter);


    lvName.setOnItemClickListener(new OnItemClickListener() {

        public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {

            String item = ((TextView)view).getText().toString();



            Toast.makeText(getBaseContext(), item, Toast.LENGTH_LONG).show();

            Intent intent = new Intent(getApplicationContext(),
                    ThirdActivity.class);
            // Create a bundle object
            intent.putExtra("ITEMNAME", item);

            startActivity(intent);

        }
    });


    btnBack.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {

             Intent intent = new Intent(getApplicationContext(),
                        MainActivity.class);
             startActivity(intent);

        }
    });


}

My problem is whenever I click on back button activity is restarted.So that first item in list is overwritten by second item.I want to get the output as list(items one by one) in second activity. whatever the data I enter in first activity.Kindly suggest me.