To answer this question, yes in most cases laptops are allowed on planes and can be taken on in your hand luggage. However, depending on the airline and country you are flying to/from certain bans and restrictions may apply.
United States
In 2017, the US government banned laptops on flights from certain airports in the Middle East and North Africa. However, in July of the same year, the ban was ended after four months. This means that laptops are allowed on planes flying to and from the United States.
United Kingdom
The government in the United Kingdom also implemented a similar ban in 2017. However, the UK Government lifted restrictions on carrying large phones, laptops and tablets in the cabin on all UK bound flights. (see our FAQ below for further information)
Global
Travelling from outside of the UK or USA with your laptop? Laptop policies around the world generally allow carrying devices in hand luggage, but recommend that you check with your airline and departure/arrival airports for any regional restrictions or security screening procedures around bringing laptops into the country.