Traditionally, wicket-keepers were chosen in international Test sides primarily because of their wicket-keeping abilities. Wicket-keeping is regarded as the most strenuous fielding position, due not only to its physical demands but also its mental and psychological ones, and teams would therefore choose wicket-keepers based first on their merits with the gloves. This caused Test nations to select players who could specialize in wielding the gloves. This type of specialization would often lead to these players focusing less on their batting.
In the 1990s, teams started fielding wicket-keepers who were especially talented batters. This trend began largely with Adam Gilchrist, who was Australia's wicket-keeper in Tests and ODIs. After his example, the top cricketing teams and aspiring wicket-keepers saw the extraordinary value wicket-keeper-batsmen could have for a side. Other batters who followed Gilchrist's example and have since been fully integrated into their national sides as top wicket-keeper-batsmen include MS Dhoni, Brendon McCullum, Mark Boucher, Jonny Bairstow, Dinesh Karthik, Quinton de Kock, Jos Buttler and Kumar Sangakkara.
In the modern game, wicket-keepers are often expected to contribute as much with the bat as middle order batters might be. Some, like Gilchrist, McCullum and Dhoni, are somewhat more aggressive as batters, and bat lower down the order to maximize their impact in limited-overs settings. Others, like Sangakkara, de Kock or Karthik, are more conventional in their style of batting, and contribute either as openers or in the middle order.
Notably, some international players selected mostly for their batting skills have been asked to keep for short periods of time. Ambati Rayudu, AB de Villiers, Tillakaratne Dilshan, Rahul Dravid, Marcus Trescothick etc. are among such occasional wicket-keepers.