Maybe this will help you: Types of computer viruses Category 1 - the boot sector virus The so-called boot sector virus is the oldest of all computer viruses. As the name suggests, it nests in the boot system. This is a programme which is located on the hard disk and which makes it possible to start the operating system. The boot sector virus changes the correct programme data and settings in such a way that the PC can no longer be booted. This type of virus was particularly popular in the 1980s and 1990s. Here, it was transferred to the PC from the floppy disk removable media that were common at the time. Today, the infection mainly takes place through the Internet. However, they are no longer widespread. Category 2 - the Trojan Computer virus TrojanOne of the most active PC viruses for many years is the so-called Trojan. It is usually used with the intention of damaging and spying on personal data on the PC. No PC user or Internet user is safe from it, because it hides itself in numerous seemingly harmless programmes. Often it is also found in spam mails, which are often disguised as invoices or similar. From these, it sneaks into the PC as soon as they or links in them are opened. Category 3 - Script viruses This super-category is about computer viruses that hide in scripts of internet pages, for example. Since script viruses are written in common programming languages, the browser understands them purely as scripts, executes them and in this way makes it possible for them to get onto the PC. Script viruses can be written in any programming language such as Java or Virtual Basic Scripts. They are not recognisable to the general PC or Internet user. Once they have settled on the PC, these computer viruses are able, for example, to automatically send e-mails and delete files or rename them. Category 4 - Program viruses As the name suggests, program viruses infect PCs via programs but also files in which they are integrated. Program viruses are activated when programs or files containing them are opened or executed. These computer viruses are mainly found in programmes that are downloaded from the Internet and usually come from unknown, unsafe sources. Many of them are found in free games or music downloads. Category 5 - Macro virus The macro virus behaves in principle in the same way as a Trojan or programme virus. The difference is that macro viruses are found in Word and Excel files. They are not present in programmes. Their effect begins automatically the moment a file containing the virus is opened. Mostly, the macro virus spreads via the internet by sending emails or downloading files. Category 6 - Computer worms A computer worm is a special type of virus that can spread independently and at breakneck speed. Unlike other types of viruses, computer viruses do not require the action of the PC user, who, for example, only activates the virus when he or she runs a virus-infected programme. A computer virus is predominantly integrated into e-mails. The greatest spreading occurs via so-called chain e-mails, which can send themselves automatically via the Internet as e-mails into millions of e-mail inboxes. Once there, they spread via the mailbox in the PC. This happened, for example, in 2000, when computer worms disguised as love letters reached mailboxes all over the world and caused billions of US dollars in damage. The main purpose of these computer worms was to spy out sensitive data such as passwords and destroy image files. Detect computer viruses If you encounter older computer viruses, they usually have the effect that your computer no longer shows any reactions. If you can no longer open files or if the PC does not start up or shut down at all, these are clear indications that a computer virus is on your computer. If you find files among your files where the file name is suddenly supplemented by additional characters or if you can no longer find files where they were, this can also indicate a virus. Viruses are also often to blame if their programmes cannot be opened, hang up permanently or crash. Or do new tabs suddenly open on their own without your intervention? Does your PC try to download unsolicited files from the internet or are you massively besieged with advertisements? Then a Trojan horse could be behind it. What you can do to protect your PC Basically, you should not wait to take protective measures against viruses until one or more or at least the first indications of a virus infection are already present. Indications are those for which you and your PC should be sensitised. This means quickly recognising indications that could point to a virus. You can protect yourself by not opening spam mails and by not downloading from unsafe and unknown sources. Especially when downloading free offers, the risk of a virus infection increases. Another protective measure you can take is to partition your hard disk. This means you divide it into two or more parts. The system is installed on one part and you can keep important files and programmes on the other parts. If a virus sneaks into the system area via the Internet, it can damage it, but it will not access the other parts of the hard disk. Anti-virus programme - a must for every PC You get the best protection by taking preventive action and installing an antivirus programme. This should be a good one that has a high contingent of known viruses and is sensitised to numerous indications. A good antivirus programme operates mainly unnoticed in the background and guards your entire system as well as your Internet connections. In this way, it can intercept harmful viruses and also detect and delete or block existing viruses. It should update at short intervals to be able to detect the latest virus developments and always be up to date, like the Avira antivirus programme, for example. Here are the types of viruses and a few detection options and protective measures. To be on the safe side, back up your data regularly, because if you have one, it often helps to simply delete EVERYTHING. I hope that help you.