2,4-D is one of the most recognized herbicides. Used properly, it will kill almost all broadleaves without affecting most varieties of grass. Used improperly, it can affect your grass and neighboring plants, including your perennials, shrubs and trees. To be effective, 2,4-D products need to stay on the treated area for a day or two before it rains or is watered, during which time you and your pets should stay off the area. And just because a little is good, a lot is not better, whether it's 2,4-D or any other chemical.
Some herbicides are available both as liquids and granules.
Granules are usually quicker and easier to apply. Liquids can be more accurately controlled, but they can also be affected by the wind and spray drift. Dry fertilizers can be spread by hand, by a shaker or a lawn spreader. Drop spreaders are more accurate than broadcast spreaders. Liquid fertilizers require a sprayer.