There are two types of Intent implicit and explicit intent, let see some more difference between them.

Implicit: Implicit intent is when you call system default intent like send email, send SMS, dial number.

For example,

Intent sendIntent = new Intent();

sendIntent.setAction(Intent.ACTION_SEND);

sendIntent.putExtra(Intent.EXTRA_TEXT, textMessage);

sendIntent.setType("text/plain")

startactivity(sendIntent);

Explicit: Explicit intent when you call you're on application activity from one activity to another

For example, first activity to second activity:

Intent intent = new Intent(first.this, second.class);

startactivity(intent);