A lead single is usually the first single released by a musician or a band from a given album. Sometimes, the lead single is not the first single (e.g Oasis's "Roll With It" from (What's The Story) Morning Glory?). The first single could be a radio promotion that ends up being part of an EPK. For example, Don Omar's "Blue Zone" for iDon and T.I.'s No Matter What for Paper Trail.
The lead single is special compared to other album-derived singles because the lead single will often be released before the rest of the actual album, in order to give listeners a taste of what is yet to come. This is not always the case, but it tends to be common practice with North American popular music, particularly throughout the 1990s and the 2000s with album-oriented artists.
Lead singles are often the deciding factor for consumers when deciding whether or not to purchase a not-yet-released album. That is one of the reasons why an artist's decision on what song to use for the lead single is an important one, since a disappointing lead single can turn off many potential buyers, whereas a successful one can build up anticipation for the upcoming album and hopefully persuade consumers to purchase the album when it is released.
In the 2000s, it has become a common trend to release a lead single months in advance of the album release date. It has even become common for the 2nd single to be released before the release of the album. With album sales declining year after year, record labels are taking advantage of the booming singles market. Online retail stores such as iTunes encourage record labels to release singles in advance as they are available to consumers for only 99 cents. R & B singer Usher for example released the lead single Love in this Club four months prior to his May 29 release date of his album 'Here I Stand'. The 2nd single Love in This Club, Part II was released one month before the album release date.
Currently, in the US as well as many other countries, artists will choose songs that are more up-tempo as lead singles. It is thought that up-tempo songs are catchier and listeners are more likely to pay attention to the song. Usually, in this case, a subsequent single (usually second or third single) will be slower-tempo so as to gave listeners a better idea of the range the album has to offer. Female vocalists like Mariah Carey and Christina Aguilera usually follow the up-tempo 1st single/slow ballad 2nd single formula, which usually works to their advantage. This was also a common and successful practice of '80s heavy metal bands.
In Japan, this feat is even more obvious. Japanese artists such as Ayumi Hamasaki, Namie Amuro and B'z release 4-8 singles prior to the release of their albums in order to achieve record breaking debut-week sales. The lead singles in Japan are very heavily advertised and promoted (in some cases even more than the album itself) and usually achieve record-breaking sales. In 1997 Namie Amuro's single "Can You Celebrate?" achieved first week sales of almost 1,8 million copies and eventually sold approximately 2,8 million copies. After the release of two more million-selling singles, the album achieved sales of 2 million copies (0,8 million less than the lead single). This trend has become increasingly popular. Various albums produce singles 2 or even 3 years prior to their release. Utada Hikaru's album "Distance" had produced 4 million selling singles (starting from 1999 up to 2001) and when it was released by 2001 it debuted at #1 with sales of over 3 million copies in its first week, the most than any other artist worldwide in any country. Another notable example is Ayumi Hamasaki's "I am..." which spawned 9 singles from 2001 to 2003 achieving single sales of 5,760,000. The album "I am... " debuted at #1 with almost 2 million copies sold in its first week breaking various records.