Brown spots in lawn
This appears to be brown patch, a common fungal disease on lawns. It does not usually kill the roots of turf. The grass should generate new growth eventually. Also, be sure to fertilize in fall, as should be done annually.
And, do not fertilize heavily in the spring, as this can contribute to fungal problems. Here is our website's info on brown patch which covers it thoroughly: http://extension.umd.edu/hgic/brown-patch-lawns