Butter is one of those foods that seems like it should always belong in the refrigerator, but its low water content makes it more resistant to bacterial growth than milk or cream. A small amount of butter can generally be kept at room temperature for short-term use, particularly in a cool kitchen. Salted butter is often the better choice for the counter, although salt doesn’t make it immune to spoilage.

If you prefer soft butter for toast, the safest approach is to keep only what you’ll use soon in a clean, covered butter dish. Keep it away from the stove, oven, sunlight and other sources of heat, and always use a clean knife. In a warm kitchen, especially during summer, refrigeration is the better option because heat can accelerate rancidity and deterioration.

Butter can still go bad. Watch for a strong rancid smell or flavor, mold, significant discoloration, or obvious contamination. Don’t simply scrape mold from the surface and continue using the rest. Homemade butter deserves additional caution because its moisture and milk-solid content can vary, so refrigeration is generally preferable.

For baking, you don’t need to leave butter out all day. Taking the required amount from the refrigerator 30–60 minutes before baking—or cutting it into smaller pieces to soften faster—is usually enough. Ultimately, if you’re unsure about storage conditions, follow the package directions and refrigerate it. Soft butter is convenient, but keeping it cool is the safest long-term option.