25 is Adele's third studio album, released through XL Recordings on November 20, 2015. It sold an overwhelming 14.970.000 copies globally in just under six weeks, making it by far the best-selling Album of 2015!

Titled as a reflection of Adele's life and frame of mind at 25 years old, 25 is a "make-up record". The album's lyrical content features themes of Adele "yearning for her old self, her nostalgia", and "melancholia about the passage of time" according to an interview with Adele by Rolling Stone, as well as themes of motherhood and regret. In contrast to Adele's previous work, the production of 25 incorporated the use of electronic elements and creative rhythmic patterns, with elements of 1980s R&B and organs. Like 21, Adele collaborated with producer and songwriter Paul Epworth and Ryan Tedder, along with new collaborations with Max Martin and Shellback, Greg Kurstin, Danger Mouse, the Smeezingtons, Samuel Dixon, and Tobias Jesso Jr.

25 received generally positive reviews from music critics, who commended Adele's vocal performance. The album achieved commercial success by debuting at number one in more than 25 countries, and broke first-week sales records in multiple countries, including the United Kingdom and United States.

In the US, the album sold sold 1.9 million copies after two days of availability, and 2.3 million after three, becoming the fastest-selling album of the 21st century and the best-selling album of 2015. The album reached sales of 2.433 million early on its fourth day, surpassing the single-week record for an album since Nielsen Soundscan began tracking sales in 1991, set by NSYNC's No Strings Attached in March 2000 when it debuted with 2.416 million copies. By its fifth day, 25 had sold over 2.8 million copies, 1.45 million of which were digital sales, breaking the first-week record for a digital set. In total, it sold 3.38 million copies in the US in its first week, becoming the first album to sell over 3 million copies in a week, and only the second to sell over 2 million in a single week. The album earned 3.48 million equivalent album units in the US in its first week of release, which is the largest registered figure since the Billboard 200 began tracking weekly popularity based on overall units in December 2014. 25 also achieved 96,000 in track-equivalent album units in the US in its debut week, and another 8,000 in streaming-equivalent album units, all of which came from streams of the single "Hello", as it was the only song from the album available on streaming services.

In the first three days of its second week, 25 sold over 650,000 units, surpassing 4 million in pure album sales. In its full second week, 25 sold 1.11 million copies in the US. In its third full week, the album sold 695,000 copies, surpassing 5 million sales, becoming the first album to do so in a calendar year since Adele's own album 21 in 2011. By its fourth week sale of 790,000 copies, 25 became the best-selling album in any calendar year since Usher sold 7.98 million in 2004 with Confessions. It sold 1.16 million copies in pure album sales in its fifth week, and became the first album to sell over one million copies in three different weeks. In its sixth week, the album sold another 307,000 copies at number one on the Billboard 200, becoming the first album to sell over 300,000 copies in six weeks since 2001 when Creed did so with Weathered. By the end of 2015, 25 had sold a total of 8,008,000 equivalent album units, 7,441,000 of which were pure album sales. It also sold 2,310,000 digital copies by the year end, making it the third best-selling digital album of all time behind Adele's own 21 and Swift's 1989. 25 was also the second biggest-selling album of a calendar year by a female artist in Nielsen history, only trailing behind Britney Spears' Oops!... I Did It Again which sold 7,890,000 copies in 2000. As of January 2016, 25 sold 7.6 million copies in the US. In its seventh week, the album remained at number one, selling another 164,000 units, becoming the first album by a female artist to top the Billboard 200 in its first seven weeks since Whitney Houston's 1987 album Whitney.

In Canada, the album debuted at number one with sales of 306,000 copies, breaking the record for highest first-week sales, which was previously held by Celine Dion's Let's Talk About Love, which had sold 230,000 copies. In its second week 25 sold another 145,000 copies in Canada, bringing its two-week total to 451,000 copies. This represents the eighth-highest weekly sales in Canada, as well as the second highest second-week sales for an album, just behind the 146,000 copies sold by the Canadian compilation Big Shiny Tunes 2 in its second week in 1997. The album sold 860,000 copies by January 2016.

In the United Kingdom, 25 debuted at number one on the UK Albums Chart and sold 800,307 copies in its first chart week, overtaking Oasis' Be Here Now (1997) to become the fastest-selling album of all time in the UK. Of that total, 252,423 copies were digital downloads, breaking the record for most digital copies sold in a week, and 548,000 were physical copies. After ten days on sale, it became the fastest million-seller in the UK, surpassing Be Here Now, which achieved this feat in 17 days in 1997. In its first week, 25 sold more copies in the UK than the combined sales of the last 19 number-one albums in UK on their debut week. In its second week, 25 sold 439,337 copies, which broke the record for highest second-week sales in the UK and also was the sixth biggest weekly sales of all time. In its third week, 25 sold 354,000 copies, which represents the second highest third-week sales since Take That's The Circus, which sold 382,000 copies in its third week. 25 was certified quintuple platinum by the British Phonographic Industry, with total UK sales at 1,593,530 copies. On 18 December 29 days after its release, the album surpassed sales of 2 million copies in the UK, becoming the fastest 2 million-seller in the country. In its fifth week of release, the album sold another 450,000 copies in the UK, becoming the Christmas number one. Its current UK sales stand at 2,539,346.

Elsewhere in Europe, 25 also opened atop of the charts. In Germany, 25 debuted with sales of 263,000 units, the largest weekly sale for an Album since Herbert Grönemeyer's 2007 release 12. In France, 25 became the fastest-selling album of 2015 after it sold 169,693 copies, of which 26,295 were downloads. The album sold another 129,200 copies in France in its second week, bringing its two-week total to 300,000 copies. In its third week, 25's sales rose to 132,200 copies in France, bringing its total sales to 430,000 copies, which made it the third best-selling album of the year. In its fourth week of sales in France, sales of the album further rose to 133,000 copies, bringing its total sales to 565,000 copies in the country, earning it a diamond certification there. In the Netherlands, the album debuted at number one with first week sales of over 120,000 copies. The album also sold over 180,000 copies in the Benelux in its first week of release. In Spain, the album debuted atop the charts selling 20,000 copies in its first week, while in Portugal it also debuted at number one with sales of 3,200 copies. 25 also entered the charts at number one in Switzerland, selling over 40,000 copies in its first week, receiving a double platinum certification there.

In Australia, the album sold more than 210,000 copies in five days, passing the triple platinum mark there. It achieved octuple platinum certification (560,000 units) there in January 2016. In New Zealand, 25 broke the record for the highest first week sales, selling 18,766 copies. The previous record holder was Susan Boyle whose I Dreamed a Dream sold 17,435 copies in its first week. By the end of the year, 25 became the best-selling album of 2015 in New Zealand. In South Africa, 25 achieved double platinum sales in five days through physical and digital vendors.

25 is credited to having eased the decline of the continuing downfall of album sales. Many journalists regarded the album as having an impact on the music industry by encouraging the public to return to buying physical albums, instead of downloading or streaming.