It you live in the south it might be bermuda or zoysia. If you live in the north it might be Kentucky bluegrass or zoysia. Where do you live?

Search this forum for leveling. It is mostly bermuda related, so hopefully that's what you have.

Your best pictures are taken in the shade or under clouds or a tree. There is far too much contrast in your first several pictures to see anything helpful.

I live in Michigan

Whoa! Surprised me!! Then it must be a mix of fescue (the green stuff) and Kentucky bluegrass (the brown, dormant stuff). Here are the basics of lawn care.

2. Water deeply and infrequently. Deeply means at least an hour in every zone, all at once. Infrequently means monthly during the cool months and no more than weekly during the hottest part of summer. If your grass looks dry before the month/week is up, water longer next time. Deep watering grows deep, drought resistant roots. Infrequent watering allows the top layer of soil to dry completely which kills off many shallow rooted weeds.

3. Mulch mow at the highest setting on your mower. Most grasses are the most dense when mowed tall. Bermuda, centipede, and bent grasses are the most dense when mowed at the lowest setting on your mower. Dense grass shades out weeds and uses less water when tall. Dense grass feeds the deep roots you're developing in 1 above.

4. Fertilize regularly. I fertilize 4 times per year using organic fertilizer. Which fertilizer you use is much less important than numbers 1 and 2 above.
   

Wow, awesome and simple tips - thank you. I just bought a sprinkler and timer, so that 1 hour+ rule is very helpful. And I didn't know about the tall grass rule either! Thank you again