Dermot O'Leary introduces the results from yesterday's semi-finals, and reveals which acts have been chosen to go through to the final by the viewing public and judges Simon Cowell, Louis Tomlinson, Ayda Williams and Robbie Williams, returning to the show after a three-week break. Plus, a musical performance from a special guest star.

The X Factor (UK) Season 15 Episodes...

• s15e01 - Auditions 1
• s15e02 - Auditions 2
• s15e03 - Auditions 3
• s15e04 - Auditions 4
• s15e05 - Auditions 5
• s15e06 - Auditions 6
• s15e07 - Auditions 7
• s15e08 - Auditions 8
• s15e09 - Six Chair Challenge 1
• s15e10 - Six Chair Challenge 2
• s15e11 - Six Chair Challenge 3
• s15e12 - Judges' Houses 1
• s15e13 - Judges' Houses 2
• s15e14 - Judges' Houses 3
• s15e15 - Live show 1
• s15e16 - Live show 2
• s15e17 - Live Show 2
• s15e18 - Live Show 2 Results
• s15e19 - Live Show 3
• s15e20 - Live Show 3 Results
• s15e21 - Live Show 4
• s15e22 - Live Show 4 Results
• s15e23 - Live Show 5
• s15e24 - Live Show 5 Results
• s15e25 - Live Semi-Finals
• s15e26 - Live Semi-Finals Results
• s15e27 - Live Finals: Top 3 Perform
• s15e28 - Live Finals: Winner Announcement

The X Factor (UK) Show Summary

Each X Factor judge is in charge of a different section of singers on the show. The judges do not know what section of the competition they will be in charge of until the audition process has finished. Each judge then has to pick four acts to take forward to the live section of the show. Each week the two acts with the lowest amount of public votes have to sing again in a final showdown after which the judges decide who should be eliminated. Once there are only five acts left remaining it becomes left to the public to decide who should go.