can someone confirm for me what these weeds are?

[davo2102]

  

 please someone help me, these weeds seem to have come out of nowhere but are spreading very fast 😞 front and back lawns are being affected and it’s seems like there is a never ending lot of them. What are they? Is there something in particular that causes them? How do I treat them? And is there a way to try prevent them?  So grateful for any help thank you