It seems an easy task to just melt some chocolate. But chocolate is a clever and finicky ingredient:

If you must add liquid, chocolate needs more than 1 tbs moisture per ounce of chocolate to melt smoothly. Too little liquid will cause the chocolate to seize up and look curdled.

Do not put a lid on a pan of melting chocolate or the condensation will drip down into your chocolate and will cause it to seize.

If chocolate seizes, remove the pan from the heat and try whisking it in 1 tsp of light vegetable (canola, corn, safflower, soybean, or sunflower) oil for each ounce of chocolate. This should smooth it out.

Use low heat, preferably a double boiler with the simmering water level in the bottom pan at least 1/2” below the top pan.

In actuality, a lot of people now melt chocolate in the microwave. Chop the chocolate first into pieces so it melts evenly and quickly. If you must use HIGH power, do so for only 30 seconds and then stir. MEDIUM power is safer; melt from 30 seconds to 1 ½ minutes, depending on the amount of chocolate you are melting. Open the door and stir the chocolate a couple of times as it melts. Microwaved chocolate will retain its shape, so stir it to see if it has really melted.