Texas is an at-fault state, sometimes called a tort state. When there's a crash, the driver who caused it is responsible for the damage. Texas law puts it plainly: you have to be able to pay for the accidents you cause. Most people meet that requirement by buying auto liability insurance, though a few qualify another way, such as a surety bond, a deposit with the state or a county, or self-insurance. Texas is not a no-fault state, so there is no system where your own policy automatically covers your own injuries no matter who was at fault.
The minimum liability you must carry is known as 30/60/25: at least $30,000 for injuries to one person, up to $60,000 total for everyone hurt in one accident, and $25,000 for damage to other people's property. Those numbers come straight from Texas statute (Transportation Code 601.072) and have been in place since January 1, 2011, when they were raised from the older 25/50/25, so they're stable. Because the legislature can change them, it's worth confirming the current minimum with the Texas Department of Insurance (TDI).
Here's the part that surprises people: liability does not pay to fix your own car. It pays other people's repair and medical bills when you're at fault. To cover your own vehicle, you'd add collision (repairs after a wreck) and comprehensive (theft, fire, flood, hail, vandalism, or hitting an animal). Both are optional under state law, but if your car is financed or leased, your lender will almost always require them until it's paid off.
You need proof of coverage at two moments: when you drive and when you register. If an officer pulls you over, you must show evidence of coverage on request, and Texas law specifically allows an image displayed on your phone, so a card on your screen is fine. To register or renew at your county tax office, you bring proof of current liability insurance. Behind the scenes, the state runs TexasSure, a joint program of four agencies that matches active policies to registered vehicles. If the system can't match your car to a policy, it mails you a letter to verify coverage within 10 days.