Hello Ellen,

Thank you for your inquiry and the photos.  Yes, this is moss.  Moss will grow in quickly on sites that are no longer suitable for grass growth.  Many things can impact grass growth like too much shade, soil compaction, changes to soil pH levels due to tree roots and drainage issues.  You are unlikely to be successful if you just remove the moss and reseed with grass.  You will need to assess the area for the possibility of any of the above conditions and make some adjustments.  Consider alternatives to grass for these areas as that may be the simpler solution.  Here are some links to more information to get you started.

https://extension.psu.edu/moss-in-the-lawn

https://turf.cals.cornell.edu/lawn/

Let me know if you have further questions.

Linda Svoboda

Horticulture Program Educator

Cornell Cooperative Extension of Broome County