有人能解释一下Android中的光标吗?

有人能解释光标究竟是如何工作的吗?还是代码的以下部分的流程?我知道这是子活动,但我不明白光标是如何精确工作的。

final Uri data = Uri.parse("content://contacts/people/");
final Cursor c = managedQuery(data, null, null, null, null);
String[] from = new String[] { People.NAME };
int[] to = new int[] { R.id.itemTextView };
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,R.layout.listitemlayout, c, from, to);
ListView lv = (ListView) findViewById(R.id.contactListView);
lv.setAdapter(adapter);
lv.setOnItemClickListener(new OnItemClickListener() {
     public void onItemClick(AdapterView<?> parent, View view, int pos, long id) { 

          c.moveToPosition(pos);
          int rowId = c.getInt(c.getColumnIndexOrThrow("_id"));
          Uri outURI = Uri.parse(data.toString() + rowId);
          Intent outData = new Intent();
          outData.setData(outURI);
          setResult(Activity.RESULT_OK, outData);
          finish();
     }
});

谢谢。