Answer: Moss will grow where conditions favor it, typically on damp and shady sites. What you are seeing may be a combination of moss, lichen and/or algae depending on the surface it is growing on.
When moss grows on soil it usually indicates that the soil is highly acidic, poorly drained, and/or compacted -- conditions where grass will not grow. This could happen around a house where eave troughs or gutters tend to overflow so water pounds to the ground and collects there. If it is partly due to this you could consider installing gutters to direct the water elsewhere. This might also benefit the condition of your house foundation -- it is not good for a foundation to be constantly wet.
To improve the soil so grass will grow you may need to trim trees to allow more sun to reach the ground, do core aeration and apply lime to adjust the soil pH. (Run basic soil tests to check the pH and also the fertility of the soil. Moss generally indicates low fertility while algae indicates excess fertilizer has been applied.)
Where it is growing on your house, you may want to take steps to remove it using a bleach and water solution (rinse this off any plants below.)
Some gardeners encourage moss on patios and garden walls as a decorative element, and encourage it as a ground cover in shady areas where lawn grass will not thrive. (Moss is very low maintenance compared to lawn.) You might want to consider that, or consider growing another type of groundcover instead of grass, if the area is shady or otherwise difficult to plant with lawn.
I hope this helps.
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