Expressed as a percentage, Loan-to-Value (LTV) refers to the ratio between the value of the loan you take out and the value of the property as a whole. It is the portion of the property’s value that isn’t covered by your deposit.
As of June 2023, the average house price in England was £292,000 (source:). Even with a lot of saving involved, it would take an extremely long time for most people to be able to raise the funds to buy a house outright. Therefore, the vast majority of people have to borrow, i.e. a mortgage, in order to buy a property.