If you live in England:

The NHS Bowel Cancer Screening Programme (BCSP) automatically sends everyone aged 60 to 74 who is registered with a GP a home bowel cancer screening kit every two years.

If you're 75 or over, you can request a kit every two years.  

The screening kit used in England is the faecal immunochemical test kit – known as the FIT kit.  You collect a small sample of stool on a small plastic stick and put it into the sample bottle and post it to a lab for testing.   More details can be found at https://www.gov.uk/guidance/bowel-cancer-screening-programme-overview#screening-tests

If blood is found in your sample you'll be offered an appointment to discuss having a colonoscopy to look for the cause.

A colonoscopy is where a thin tube with a camera inside is passed into your bottom to look for signs of bowel cancer.  The specialist uses a thin flexible tube (a colonoscope) with a tiny camera on the end to look inside your bowel and remove any small growths called polyps. They also use the colonoscope to check the bowel for cancer.