Thirty years ago, the Association of Residential Letting Agents and a consortium of lenders launched a mortgage product that would fundamentally reshape British housing tenure: buy-to-let. What began in 1996 as a niche offering for a handful of amateur landlords has grown into a market underpinning roughly 4.6 million private rented households across the UK, financed by an estimated £1.5 trillion of outstanding lending. That anniversary is worth pausing on, not for nostalgia, but because the buy-to-let sector today looks nothing like the one that emerged in the mid-1990s — and understanding that transformation is essential to reading where it goes next.