Knob-and-tube was the standard wiring method in homes built before the 1950s. It still works in many houses, but it has real limitations and can affect your insurance, so it's worth understanding if you own an older home.
Why it's a concern
Knob-and-tube has no ground wire, was designed for far lower electrical loads than modern homes use, and its insulation becomes brittle with age. It's especially risky where it's been buried in insulation, modified by amateurs, or overloaded with modern appliances.
Insurance and resale
Many insurers won't cover homes with active knob-and-tube, or charge more, and buyers often ask for it to be removed. An electrician's assessment documents its condition and what a replacement would involve.
Your options
You don't always have to rewire the whole house at once — an electrician can prioritize the highest-risk circuits. A full rewire is disruptive but resolves the safety, insurance, and resale issues permanently.