Gas and Oil Home Heating Furnaces - Noisy pipes

We bought a house last summer that has a very old boiler (my guess is at least 25 years old). It is a forced hot water system. The baseboard in our room makes noises as it warms up and cools down. However, we can also hear a noise that sounds like a loud tapping noise, almost like the sound of a leak in the room through a sound amplifier. I am pretty sure it is not a leak but somehow related to our heating system, perhaps some sort of tapping noise in the pipes. Any idea of what the noise can be and how to fix it?

I'd start with bleeding the air out of the baseboard radiators, and see if that eliminates the noises. Review previous posts in this forum if you need directions on how to do this.