Audience of this letter would be a higher up person in the work placement. Meaning this person is an adult, and as this is talking about his job the letter is in a format of formal. The purpose of this text is to inform that this person is leaving their job in a certain dates time. The language he uses is polite and respectful. The worker talks about how he/she respects his opportunity to work where he is now.
Technology came into this as this is computer typed rather than hand written, making this more formal and a better way to make a clear point that he/she is leaving