Every day police forces up and down the country appeal for the public's help as they search for information or people.
While most of the time we may not have seen what happened, or who police are looking for, occasionally we may witness something which could aid police investigations.
There's a variety of ways this can be reported, and in today's modern world doing so online is easier than ever.
See the video above to find out how to report information with Metropolitan Police.
On its website, Met Police says: "If you've witnessed or been the victim of crime in London, help us to bring the offender to justice and make sure this doesn't happen to anyone else by reporting it here.
"Just answer a few quick questions below to find out the best way to get in touch.
"The kind of information you provide here plays a huge part in how we plan our policing of London."
Report crime on the Met Police's website at beta.met.police.uk/report/how-to-report-a-crime/ .
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