Question on making offers

[Josiah Collins]

In many of the posts and blogs I've read here there is one thing that isn't super clear to me. I see how people mention that they will get a property under contract then look for a PML or HML. How is it that people are making offers without first having the money or a loan? Are they getting preapproved for a loan only? I ask because it seems like all of the posts I've seen say to attach a proof of funds or preapproval. I'm sorry if I'm just missing something super basic here! Thank you!