In one sentence, describe what the following article is about:

Start by moistening the seed-starting medium thoroughly, so that it provides a good growing environment for the seeds. Fill the containers with the medium, leaving about 1⁄2 inch (1.3 cm) of space between the top of the growing medium and the rim of the containers. Place the containers in a sunny, well-ventilated area with a steady, warm temperature. The way you sow your seeds is depending on what type of plant you're growing, so it's necessary to read the seed packet carefully first. Many seeds can be scattered evenly across the surface of the growing medium. Be sure not to place too many seeds in the same growing container, since you don't want them to crowd each other too much.  Most seeds should be planted twice as deep as they are wide. Some seeds should be planted about 1⁄2 to 1⁄4 inch (1.3 to 0.6 cm) below the surface of the growing medium. Check your seed pack to make sure you sow the seeds correctly. Some seeds do best when they are chilled or soaked before sowing. Be sure you're providing the right sunlight conditions for your specific seed species. Most seeds can germinate without light, but they'll need sun as soon as they sprout. Most seeds do best with a temperature of about 78 degrees, but some need colder or warmer conditions to germinate. Seed growing medium tends to dry out quickly, since there's no soil to hold the water. Be sure to water the seeds consistently, never allowing them to dry out too much.  You can lightly drape a piece of plastic wrap over the seed trays to help trap in moisture.  Don't overwater the containers, or the seeds could become waterlogged. They should be moist, but not dripping wet. As the seeds sprout into seedlings, you'll see thin green stems emerge from the growing medium. If the containers aren't already placed in a sunny area, be sure to move them to a place with direct sunlight or provide them with grow lights overhead. Keep them moist at all times and make sure the temperature never drops below the recommended level. You can place a heat mat under the seed starting tray to maintain the correct temperature. After a week or two, weed out the weaker-looking seedlings so that the stronger ones have more room to grow. Leave about 2 - 3 seedlings per container.

Summary:
Prepare the growing containers. Sow the seeds. Keep the seeds moist. Keep the seedlings healthy. Weed out the weaker seedlings.