Yes, dandelions are considered perennial, broadleaf weeds.

Technically, dandelions aren’t bad for your lawn, and they don’t directly kill grass. In fact, they appear in areas that are nutrient-deprived, and their long taproots can loosen the soil and bring nutrients closer to the surface. 

However, dandelions do spread quickly, and they can take over your lawn, eventually crowding out grass. This is why a healthy lawn is the best defense against dandelions.

Pulling weeds once per month is typically often enough to keep most weeds at bay. But in general, it's best to pull weeds as soon as you spot them to prevent deep root growth and slow their spread. To make it easier, plan your weed pulling after rain or after the sprinklers run so the soil will be nice and wet and the weeds will be easier to pull. If you notice moss accompanying weeds, make a plan to remove the moss immediately to prevent damage.

Several tools exist that can help remove unwanted grass. The one you choose depends greatly on how much you need to remove and how hard you'd like to work. A sod or turf cutter is the fastest method while using a shovel is labor-intensive and much slower. You may also need a garden rake, tiller, and wheelbarrow.