If you find yourself facing allegations of criminal activity, one of the simplest ways to show that you are not guilty of the crime is to demonstrate that you had an alibi.
Essentially, an alibi is simply evidence that you were somewhere else when the crime took place. While anyone can insist that they were somewhere else, an alibi that holds up is generally one that can be backed up by evidence or the testimony of someone else.
For example, perhaps you are accused of breaking into a home. The incident was caught on camera, and the suspect does resemble you on the footage.
However, you were out to eat with a business partner at the time. That's your alibi. They will back you up, saying that you were in fact at the restaurant 10 miles away from the break-in, so there is no way that you could have committed the crime.
In addition, perhaps you paid for your meal with a credit card. This gives you a paper trail that can also back up your claim. You can show what you bought, how much you paid for it and when you purchased it. In some cases, people are cleared because it's obvious they could not have made it from one location to the other fast enough to commit the crime -- such as when the timestamp on the security footage and the time on the receipt are just a few minutes apart.
This is just one example, and an alibi can take many forms, but it helps to show why you need to carefully consider all of your options when facing legal charges.