What should I do about cracks in the foundation/crawl space?

Newer home owner here. I have these cracks on the foundation of the house. Behind them is a crawl space open to dirt. How should I fix or address these? Do they need to be fixed? I try and DIY as much as I can so don't be afraid to suggest a DIY solution. I'm also not above getting professional help, I just haven't had to thus far.