Glass is made up of silica, sodium oxide, and other ingredients. However, borosilicate glass is a specific type of glass that contains boric oxide instead of sodium oxide. This makes it stronger than regular glass, making it useful in applications where high temperatures are involved (like space shuttles). Borosilicate also holds up better against thermal shock than regular glass does and will not shatter easily when dropped on the floor or exposed to sudden changes in temperature like regular glasses can do.
When you're shopping for kitchenware, you'll notice that most glassware is labeled with either "borosilicate" or "soda lime." The former will likely be more expensive than the latter.
Borosilicate glass is useful for a variety of applications, but it's particularly effective at withstanding thermal shock. Thermal shock occurs when a material heats up quickly and then cools down quickly. This sudden change in temperature can cause cracks or other damage to occur in the material. Borosilicate glass is most commonly used as cookware, laboratory equipment and even space shuttles because it's resistant to this kind of damage.
The main ways to tell borosilicate glass from other types of glass is by its price, its heat resistance and transparency, and its scratch resistance.
The temperature rating indicates the maximum temperature that a piece can be heated or cooled to without breaking. A lower number means it will break more easily at higher temperatures; for example, an object with a rating of 450 degrees C is less likely to break than one rated 350 degrees C. It's also worth noting that while manufacturers often provide these ratings, they may not be accurate—and it's important to know how much variance you should expect in your own work situations so that you don't inadvertently damage your pieces by exposing them to extreme conditions.
The next way you can tell if the glassware is borosilicate is to try putting ice cubes in a liquid like water or lemonade, and see how long it takes them to melt. When you put an ice cube into water, it will most likely melt faster than when you put an ice cube in soda. If the glassware has any kind of sweetener in it (like sugar), then this test won't work so well because sugar will keep your drink cold for longer and give off heat slower.
Another thing that causes this effect is acidity--if there's any acidic ingredient in your drink (like juice), then this test may not work as well either because sugar isn't as effective at keeping things cool when there are acids present too!
With all this information in mind, you should be able to tell if something is borosilicate glass or not. If you're still unsure and don't know how to identify it by sight, go ahead and ask someone who does!