If you are invited to the party with your friends and family, most of them will notice that you are there. It is necessary to say hi and hello to your friends and family when attending a party. It also depends on what type are you attending with, party, meeting at work, or friend, or anything that you are invited or needed your presence. If attending at work meeting,of course they will surely notice your because you have to log in your details that you were there. If you cannot attend, they will also question you why you were not there during the meeting. Do not be cautious if people will ot not notice you when you are attending, just be there and be your self and enjoy the party or pay attention if you are attending a meeting. Especial moment like this no need to be questioned about.