Via convection.
Conduction is one way that heat spreads.
Heat transfer in a kettle occurs through conduction. The heat from the stove is transferred to the bottom of the kettle, which then spreads throughout the kettle via conduction, causing the water inside to heat up. Heat is also transferred through convection as the hot water rises and circulates within the kettle.
Sun warms the Earth (and the water); Earth (and water) warms the air. Edit: The simple answer is that the atmosphere and the oceans spread heat around the Earth, because they are fluids.
Are you asking why ink spreads and paper doesn't when water is spilled on a page? Ink is water soluble so it dissolves and spreads. Paper is not water soluble (although it will get soggy) so it doesn't dissolve.
Microwave ovens heat up food by emitting microwaves, which are a type of electromagnetic radiation. These microwaves cause water molecules in the food to vibrate rapidly, generating heat. This process is known as dielectric heating. The heat produced by the vibrating water molecules then spreads throughout the food, heating it evenly and quickly.
A water bath or a heating mantle are examples of lab equipment that can diffuse or spread heat evenly. These tools provide a controlled and uniform heat source for samples placed within them, allowing for consistent heating of materials.
Unless you bought 'cold brew' tea, then you have to heat it. You can make 'sun tea and leave it out in direct sun in cold water, and let the sun heat the water and make the tea, without heat, tea in cold water will make very mildly tea flavored water.
water
Heat is the vibration of atoms. One atom hits its neighbour and the vibration spreads - it is called "conduction".
Waves, as in water, or electromagnetic radiation. Even a beam spreads out, due to diffraction.
Through an elaborate system of ocean currents. Water is cooled at the poles and sinks, because it is a little more dense than warmer water. The cool water moves around the ocean floor and spreads toward the equator, generally, and warmer water moves up at the equator and spreads out along the surface.
Heat energy is transferred from hot water to surrounding air due to the temperature difference between the two. Heat always moves from a hotter object to a cooler one in an attempt to reach thermal equilibrium. This transfer occurs through conduction, convection, and radiation.