Photo by Fanny Schertzer (Own work) CC BY-SA 3.0, via Wikimedia Commons
Bike tires are filled with pressurized air so the ride will be smoother and more efficient. Unlike cars which mostly use tubeless tires, bikes need innertubes because most bike rims have holes for the spokes, and these would be hard to seal. So, an inner tube, which resembles a donut-shaped balloon is used to seal in the air.
Keeping weight down is important for bicycling, and weight that spins is more critical than non-spinning weight. Therefore, inner tubes are made as thin as practical. Because of that, you need to be careful removing and installing inner tubes.
Removal can often be done without tools. If tools are needed, try to avoid using screwdrivers. Tire levers, specially designed for the purpose are best. In a pinch, you can carefully use the backs of silverware.
When inner tubes are punctured, they can be patched, or replaced. Because bicycle tires should not weigh as much as car tires, they are more prone to punctures. Far more prone. So much so that bike riders often prefer to carry facilities to repair punctures on the road. These involve a pump, possibly tools to remove the wheel and tire levers, and a replacement inner tube or patch kit.
Whether you carry a patch kit, replacement tube, or both is a personal decision. A patch kit is limited in that it can only repair a certain number of punctures, and only punctures of a limited size. Hit a patch of thorns, and you’ve had it. Patch kits that have glue are prone to the glue drying. Patching takes longer than replacing a tube. However, an inner tube will repair only one puncture. A second puncture will end your ride. Keep in mind also that a tube can be destroyed in storage or installation.
You’ll find complete instructions for fixing a punctured inner tube at BikeWebSite.