[Samsung Galaxy Note 9 Questions & Answers] Qui Peccavit:
The usual suspects call for the usual sheriff

Please excuse me if I am missing something here, but ...

... as long as you install apps from trusted sources only, there are people who argue that malware protection software is not necessary on Android or iOS, because the community here, major alternative app markets and of course the Google Play Store detect malicious applications as long as the respective settings have been configured correctly.

If you do not want to rely on those mechanisms alone because in the past, there were indeed infected apps on the Play Store and iTunes, then you detect, fight and prevent malware on mobile devices with the same tools that you use on laptop and desktop computers, i.e. with a good antivirus and firewall. All major manufacturers offer security suite packages for 3/5/10 devices and 1/2/3 years, meaning you can install the software on a PC, iPad, Android phone or iPhone. There are basically the following criteria when selecting a good security suite -- simplified and abbreviated, but hopefully sufficient as an overview.

Detection rate (finding all the bugs and critters out there as soon as they begin to float around). When seeing comparisons, do not pay attention to percentages differing within the last few percent, i.e. for detection rates over 97%. These differences often stem from the time of the latest update -- the software that was just updated five minutes ago catches the latest threat, the other program will catch it in three hours, when they update their signatures. Most computers do not get infected by today's nasties, but by old s..t in combination with user laziness and stupidity -- the 0-hour bullet points are merely necessary for marketing, because within a few hours, all top-tier manufacturers have their signatures updated and provide the same protection.

Absence of false positives. Many antivirus/firewall manufacturers flag cracks, key generators and the like despite being perfectly clean, to 'disencourage' the use of those little helpers or because they are too dumb to distinguish between infecting activities or merely circumventing some security protocols to get their job done. The problem is that these programs have a tendency to erroneously flag and block many legitimate and legal activities as well, nerving the user with alerts all the time or worse, applying default settings in the background that have you wonder why something does not work.

Efficiency/performance/resource hunger. Security measures that are too inconvenient, complicated or slow tend to be switched off by workers sooner or later, and the best protection in the world is not worth staring at the hourglass every few minutes, waiting for a scan to finish. A good security software does its job in the background, without slowing down the machine or grabbing hundreds of megabytes of memory.

Smart procedures: this is the hardest thing to compare and evaluate, because reviewers rarely pay attention to details and do not use the programs long enough to notice silly design. One example: downloads being halted and files scanned before being written to the hard disk. This often breaks the downloads of larger files, when the scanning time is longer than the browser timeouts, and if the server does not support 'Resume', you will be swearing at the antivirus all day long. Clever security software will either allow downloads to finish by default or at least provide a configuration setting to make this happen. It should also be easy to recognize and whitelist false positives, without requiring an act of parliament, a presidential executive order or digging through a thousand submenus with advanced settings and a truckload of confirmation dialogues.

There are review sites for security software that go into the length and depth of all this, evaluating all but the last point repeatedly. At the time of this writing in March 2019, in case you do not want to dig through endless tables with details, the best antivirus/firewall (nearly everything else are gimmicks) security suites are in alphabetical order, BitDefender, ESET, Kaspersky and Norton, with Comodo being a free alternative and Dr. Web a choice for certain special circumstances. There are a few others that use vector/pattern recognition/artificial learning and other technologies to avoid having to rely on signatures (which makes them look bad in traditional, signature-based comparisons), but presenting these would go beyond the scope of a forum post. There are antivirus/firewall/security sites that explain all this in detail and recommend the best tool for special needs and purposes.

While you may decide to not need a security software for your phone, only a fool uses a personal computer without protection. :silly: :D