OK, you want to buy a house but you really don't have $200,000 or so lying around (not too many people do

). So you go to a bank, credit union, or mortgage lender for a loan. Well, since that's a ton of money to just lend somebody - what if you don't pay the loan back? -
you give
them (this is what most people don't realize) a mortgage on your house or property. A mortgage is simply an agreement that, if you don't pay the loan back, the bank/credit union/mortgage lender can then take the house (forclosure). You would need to move out. The bank would sell the house to pay off your loan. They usually don't want to do this and so it usually takes like not paying for 6 months until the bank gets to the point of forclosure.
When you take the loan out, you decide how long you need to pay the loan back - 10 years, 15, 20, 30, even 40 year mortgages are out there.
So this is why adults can get headaches over mortgages. That's one bill that
has to get paid every month so your family has someplace to live.
This is kind of a nutshell. There's more involved - escrow (additional money you need to pay each month for Real Estate and School taxes); interest rates; blah, blah.
Hope this helps.