Laptops were personal computers used on Earth.
The Xylok later known as Mr Smith first communicated with Sarah Jane Smith using her laptop. (TV: The Lost Boy)
Victor Kennedy possessed a Vaio brand laptop which he used to access the LINDA website, Who Is The Doctor?, in his office. By using a handheld device, Victor was able to trace LINDA's location to Maccateer Street. (WC: Tardisode 10) Later, when he met with LINDA in basement unit 4b, Victor was in possession of a PowerBook G4 laptop which he used to play footage of the Tenth Doctor and Rose Tyler entering the TARDIS, and the following sound of it dematerialising, to the members of LINDA. (TV: Love & Monsters)
The Eye-5 lens could be connected to a laptop computer. (TV: Children of Earth: Day Four, Dead of Night)
The SerfBoard was a type of laptop computer. (TV: The Man Who Never Was)
Jeff Angelo had a laptop which the Eleventh Doctor used to hack in on a conference call between some of the most advanced scientific minds in the world in an effort to spread a computer virus to show the Atraxi where Prisoner Zero was and therefore save the Earth from incineration. (TV: The Eleventh Hour)
Clara Oswald had a laptop which the Eleventh Doctor used to reverse her upload by the Great Intelligence. Clara later used it to find out where Rosemary Kizlet's organisation was based, and the Doctor controlled a Spoonhead with it to confront Miss Kizlet and force her to restore everyone trapped in the data cloud. (TV: The Bells of Saint John)
Most of the Coal Hill defenders had laptops. (TV: For Tonight We Might Die)
After Petronella Osgood explained how 'everything' in the UNIT database had been 'heavily corrupted with huge chunks missing', Cleo Proctor joked that it sounded "like [her] laptop after [her] brother downloaded that dodgy copy of Pirates of the Caribbean 4". (AUDIO: Recruits)
Mickey Smith had a laptop, (TV: Rose) which he used to access the UNIT website under the Ninth Doctor's direction to gather information and commander Royal Navy systems. (TV: World War Three) When the Sycorax invasion of Earth drew the attention of the Third Doctor and his companions, Jackie Tyler, thinking Mike Yates was a regenerated Mickey Smith, pointed out Mickey's laptop, the UNIT captain doubting that the small device was indeed a computer. Instead, the Third Doctor used the laptop to bring himself up to date. (PROSE: The Christmas Inversion)