There are many reasons why as a borrower, you would want to apply for a mortgage. The most obvious is that you cannot afford to buy the house in cash and need to make installment payments on it over the next 15 to 30 years.
Even if you are not buying an investment property and could afford to buy the house in cash, there are still valid reasons to apply for a mortgage. For instance, you'll have more cash on hand for other investment opportunities by having a mortgage.
Because the prospect of getting a mortgage can be daunting, it helps to break down the process of applying for a mortgage into steps. It is really a process, and each step has a few things that need to be done by you, the borrower.