What is a one-sentence summary of the following article?
Park the car on a level surface and engage the parking brake. Park at home or at an auto garage if possible. If it turns out you can't fix the problem on the spot, you don't want to be forced to close your hood again to drive to a mechanic. If you're not familiar with the car, look for the interior release latch under the steering wheel, low down near the driver's door, or in the corner of the glove box. This often has a picture of a car with an open hood.  Some older cars only have an exterior release. Look for a latch under the front lip of the hood. If you are locked out of the car, skip ahead to fixes that do not require interior access. When working correctly, this causes the hood to move upward a short distance. If you hear a noise but the hood does not move at all, the hood is probably stuck. Continue to the next step to fix it. If you do not hear anything, there's likely a problem with the cable or latch mechanism. Skip down to the next section. If the hood does open partially, all you need to do is press the exterior latch at the front of the hood. This latch is usually at the center or just to one side, and may depress upward or to the side. Stand outside the driver's seat and reach in to hold the interior release in the fully pulled position. With your other hand, slap the hood with an open palm. If you're lucky, the hood just needs a jolt. Take care not to dent your hood. You may need to use force, but keep your hand in an open palm position. Have a friend pull the interior release and keep it in that position. Stand at the front of the vehicle and pull up on the hood slowly but steadily. If the only problem is rust or grime, you can usually overcome it. If the hood won't budge, don't force it. Chilly weather or frost can cause the hood to stick. Let the engine idle for a while to thaw frozen parts, then try opening the hood again. If the hood still won't open, the cable or latch mechanism might be at fault. Continue to the next section to keep troubleshooting. Once you get your hood open, check for broken latch parts or a frayed cable, which needs replacing. If you don't see obvious problems, just lubricate the latch with a penetrating oil.  It may also help to lubricate the cable with a spray lubricant. Insert the straw nozzle at the cable's end, between the inner cable and outer sheath. Pinch the area with a cloth and spray. Do not use silicone spray under your hood. It can contaminate the oxygen sensor, throwing off engine performance.

Summary:
Park the vehicle. Locate the release latch. Test the interior release latch. Slap the hood to get it unstuck. Attempt to open the hood with an assistant. Leave the engine running in cold weather. Inspect the latch after opening.