Use shared preferences like this:
SharedPreferences myprefs= this.getSharedPreferences("user", MODE_WORLD_READABLE);
myprefs.edit().putString("session_id", value).commit();
You can retrieve this info across your app like this:
SharedPreferences myprefs= getSharedPreferences("user", MODE_WORLD_READABLE);
String session_id= myprefs.getString("session_id", null);
You should use intents when you want to start another activity from your current activity… also if the child activity is totally dependent on data from parent activity …use intents