How do you introduce a song?

Is it always necessary to do so?

Are they any 'hard and fast' rules as to 'setting up a song'?

Is it possible to actually detract, from the song by the way it is 'set up'?

Can you 'set it up ' so well that it is then not necessary to actually sing the song?

Would you always introduce the song, in exactly the same way, each time you performed it. With the same jokes and 'spontaneous' ad-libs for example?

How do you feel about the way songs are introduced to you, as an audience member?

There are some performers I have gone to see sing and at the end of the performance, realised just how few songs were actually possible to fit in, given the lengthy introductions (and constant re-tunings). And entertaining as those introductions may have been, I usually feel a little cheated. Some performers have even moved from singers who did amusing introductions, to entertainers who occasionally sing the odd song. I am thinking of people like, Billy Connelly and I am sure there are other examples?

I am sure too that there are many examples of those you would consider to have the balance just right and those that have it wrong?