If you can put icing on a cake, you can do a good caulking job. It’s a piece of cake! You load a tube of exterior-rated caulk (same color as the siding, or close) into your caulk gun, squeeze the trigger – and out comes the caulk. You can trim the size of the tip to get the desired thickness. Then you just run your finger along the edge to smooth out the bead of caulk and – viola! – nice job! Once the new caulk dries, you can paint it to match the siding. They even make electric caulk guns now, which I suppose would be nice if you have a whole house of wood siding to caulk up.
It’s important to seal any and all openings in the outside wall of your home, the “building envelope.” Caulk is the standard solution for small cracks. Water can – will! – get into any crack, especially on the windward side of the house. That water will cause rot in the siding and wood framing, even the wallboard. It will soak into the fiberglass insulation and render the insulation value equal to zero. Zoom, zoom – up goes your heating and cooling bill. Cracks violate the moisture barrier and allow moisture to flow freely into the whole house.
Long term, all that moisture in the walls can spawn mold – at which point you have a major problem, bad enough to maybe even have to gut the whole structure down to the framing and start all over again. Mold can cause serious health problems, too. Any moisture entering a structure has to be extracted by the HVAC system, which costs good money.
So, please, buy yourself a caulk gun and have an afternoon of fun, giving your house some much-needed TLC. If you notice lots of cracks everywhere, like between the paneling, it might be time to call a painter and let them caulk everything, then put a couple of coats of quality paint on the outside – a new look! (Choose light colors in warm climates, darker colors in cold climates.)