In the stricter sense of the word, cooking means submerging food into boiling water of 100°C. Water boils as soon as steam bubbles are created at the bottom of the pot. Poaching or simmering occurs when the water is just below 100°C. The advantage then is that no air bubbles are created that could split fish or fine vegetables.
For optimal cooking in a pot/pan, the walls of the pot should not pull heat from the bottom upwards. The heat must be contained within the pot/pan by the wall and the lid. A good bottom must be heat-conducting so that the heat is evenly distributed over the bottom.
1. Never leave an empty cooking utensil on a hot cooking facility, never let it cook or boil dry. This could deform or melt your product.
2. Only put a warm lid reversed on a glass cooker plate. Otherwise, the cooling process could create a vacuum which would make it difficult to remove the lid.
3. Non-dissolved salts could create small indentations in stainless steel bottoms. Do not leave food with a high salt content in your pot.