The main criminal offense covering intoxicated drivers is driving while intoxicated - or DWI. That's different from many states, where the offense is driving under the inluence - or DUI. Texas does have an offense of DUI, but it only applies to minors.
If you're a minor - which means you are under 18 - you commit an offense if you operate a motor vehicle (or watercraft) while having any detectable amount of alcohol in your system. Basically you can't drink and drive; which is the only time the phrase "don't drink and drive" has any validity. The state doesn't have to prove you are intoxicated, simply that you have alchohol in your system.
So how do they prove you have "a detectable amount" of alcohol in your system? Police rarely take minors in for a breath test, or blood test, unless they believe the minor is intoxicated. Instead, the decision to charge you generally is based on the odor or smell of alcohol on your breath. Not exactly scientific, but that's a separate discussion.
The offense of DUI is a class C misdemeanor, which is similar to a ticket. However if you've been convicted of the same offense twice before, the punishment is increased to a class B misdemeanr, and you can be sentenced to up to 180 days in the county jail. In addition to the fine, community service is mandatory; 20 - 40 hours if it's a first offense, and 40-60 hours if you've been convicted before.
In addition to a fine and community service, there is also a mandatory alcohol awareness class that must be completed. If you don't complete it within 90 days (unless extended by the court) your license will be suspended for a period up to 6 months, or if you don't have one prevent you from getting one for up to six months.
As you can see, just because you aren't going to jail doesn't mean DUI is a minor offense. Before you go in and plead guilty make sure you know the consequences - and the alternatives.