The reason there are so many dandelions is because of excess moisture in the soil and sunny days as well as warm periods.
Dandelions are a problem for lawns as the dandelions absorb and take away moisture from the soil that is needed for the grass and because of that the grass may not get enough water that it requires to survive.
Dandelions also form dense rosette leaves that crowd out grass and reduces the grass strength.
A dandelion puff is called a pappus which allows the seed to be carried by the wind.
Dandelions do sometimes indicate you have poor soil and can indicate that your soil or lawn has an excess of potassium and or a deficiency of calcium.
Dandelions also thrive very well in compacted soil and also love acidic soil.
Dandelions in lawn mean that there is excess moisture in the soil and sunny days as well as extended warm periods which encourage the growth and the germination of dandelions.
The amount of dandelions that you have in your lawn can also be attributed to the previous year's growing conditions.
You should let dandelions grow in your yard as dandelions are actually good for your lawn and the wide spreading roots of dandelion plants also loosen hard packed soil, aerate the earth and also help reduce soil erosion.
The deep taproots of dandelions also pull nutrients like calcium from deep in the soil and make the nutrients available to other plants including grass.
Dandelions grow in all states in the United States and also in Canada and they also tolerate a wide range of conditions.
If you want to get rid of dandelions you should pull them or dig them out and spray the dandelions or area where you pulled the dandelions with some herbicide.
Mowing them will also keep them down but they will grow back until you mow again.
Dandelions will grow back if pulled out even when you pull the deep taproot they can grow back.
But if you pull the deep taproot they are not as likely to come back as they would if you just simply pulled them out.
If you don't want dandelions in your yard you can spray them with some herbicide.