There are only two reasons to ever use technology when giving a presentation:
It makes it easier for your audience to understand or remember your key points.
It makes it easier to accomplish your goal of making your audience understand and remember your key points.
Please note your relative order of importance: you come second to the audience. Why is it important to point this out? Because quite often inexperienced and average speakers will say things like, "I don't need a microphone." Well, obviously, the speaker never needs a microphone to speak. But some of your audience members may need you to talk into a microphone that is then amplified into a speaker if they are going to hear you. Unless you are talking to two people sitting right in front of you, you can never be certain if people need you to use a microphone or not.
I actually take my own wireless microphone with me wherever I go to speak; and I recommend that all professional speakers do so. But you don't have to. Let's keep things simple. My recommendation is to simply use a microphone anytime you are in a room that has one or someone offers one to you. Of course, if you are in a room that holds 500 people but you are speaking to only five people, then you don't want to be far away from the people on a stage just to get close to a microphone. In that case, you would just get as close as possible to the five people and speak. ...