Here is our guide to the bugs and what you should do about them.
* Meltdown and Spectre are bugs affecting microchips - which nearly all computers use.
* Meltdown affects laptops, desktop PCs and servers with Intel chips. Spectre affects chips in smartphones, tablets and computers with Intel, ARM and AMD chips.
* Data devices connected to the cloud are also vulnerable.
* Gaps in the chips' security have recently been exposed, and there are fears hackers could breach them - although this hasn't happened yet.
* The tech industry has known about the problem for around six months, but the information wasn't made public while they attempted to fix the flaws.
* Around 90 per cent of PCs are powered by Intel chips.
* The bugs enable a hacker to discover information stored on a PC's memory, such as passwords and even credit card data.
* Microsoft, Apple and Linux have all created security updates called 'patches' to protect against Meltdown, and these are expected to be made available soon.
* Apple's products, including Macs, iPhones and iPads, are all affected, apart from the newest version of the iOS software, 11.2 They are also releasing anti-Spectre updates this month.
* Microsoft's emergency patch was released on Thursday.
* Google said Android phones with the most recent security updates are protected, and users of web services like Gmail are also safe. Chrome web browser users are expected to receive a patch later this month.