Windows does not show file extensions (that is, show the type of file) by default; this is extremely dangerous. A file with the name 'safe-word-document.docx.exe' will be displayed as 'safe-word-document.docx' in the file browser; someone can send you a malicious executable by mail and root your machine. Go to the 'view' tab in the File Explorer and check the 'File name extensions' box on the right side.
Windows Defender is the default antivirus tool for Windows and is included as part of the operating system. If the machine comes with Norton/AVG/Avast/McAfee/etc, uninstall it with prejudice; not only are they nagware, but they cause enough havoc to be a virus in their own right.
One of the vectors for malware and scams is email. First by phishing - emails that purport to come from your bank, for example, and ask for you to 'verify' your login information. The more sophisticated scams will create clones of the bank's website and link you from the email; always use the website address listed on official bank communications, such as your statement. Next, hostile attachments in emails; PDFs, Word documents, and Excel files can all contain malware. PDFs can contain extensions that will exploit bugs in Adobe's PDF reader to install malware; use the Sumatra PDF reader unless you need the extra features, such as filling in forms on a PDF. Word and Excel documents may contain macros - a set of instructions - that will install malware when opened. LibreOffice is a free and open source document editing suite that can replace most Microsoft Office use cases. Never run executables sent to you by someone you wouldn't trust with physical access to your computer. (A fun fact: emails are essentially post cards - their contents can be read by every computer it passes through on the way to the recipient. Don't send personal information over unencrypted email.)
Technically proxy services. Aside from rolling your own, Mullvad is the only one I can recommend. Read the documentation to ensure you aren't leaking identifying data in some other manner.
Download and run; select 'actions', 'apply recommended settings'. Disables Cortana, data collection, lock screen advertisements, start menu advertisements.
Chrome is a data collection tool and advertisement delivery platform for Google. Microsoft Edge is a reskinned Chrome with even more non-features.
Concerning security and customizability, Firefox has no competitors. Unfortunately needs a bit of work to disable some non-features. Right click the menubar, select 'Customize Toolbar'. I always drag off the spacers and the unnecessary items and drag the 'Addons' and 'Settings' icons onto the toolbar. Go to 'Settings', click the house icon. Uncheck 'Recommended by Pocket'. Go to the menu, choose 'Preferences', go to the general panel, uncheck 'CTRL+Tab cycles through tabs in recently used order'. Remember that the Bookmarks Toolbar can be hidden or displayed in CTRL+Shift+b. To move the cursor to the address bar: ALT+d. To reopen a tab you accidentally closed: CTRL+Shift+t. To reopen a window you accidentally closed: CTRL+Shift+w. Peruse the manual.
See also, useful customizations, about:config.
Keep in mind that more and more addons are used for data harvesting or are outright malware. The situation is much worse on the Chrome webstore, however. When in doubt, read the reviews, and read the source code of the addon in question.
The King of ad blockers. It's actually "a wide-spectrum content blocker with CPU and memory efficiency as a primary feature" in the words of the author. Stops ads, trackers, coin miners, popups, etc. - and can also block JS locally or globally. You can write your own global or local rules to override or customize filter lists. I strongly recommend reading the documentation. One of my favorite features is the manual element blocker - right click on a webpage, select 'Block Element', and then click on the part of the webpage you want to block. Does a site you visit have an annoying floating header, or obnoxious sidebar? Click and block it. I wouldn't browse the web without this tool.
An adblocker is also a must from a security perspective - malicious JS loaded in through ads is a major vector for malware and data harvesting tools.
From the developer: "Websites have increasingly begun to rely much more on large third-parties for content delivery. Canceling requests for ads or trackers is usually without issue, however blocking actual content, not unexpectedly, breaks pages. The aim of this add-on is to cut out the middleman by providing lightning speed delivery of local (bundled) files to improve online privacy."
Aside from stopping some tracking, it makes some websites load faster.
"Privacy Badger automatically learns to block invisible trackers. Instead of keeping lists of what to block, Privacy Badger automatically discovers trackers based on their behavior. Besides automatic tracker blocking, Privacy Badger replaces potentially useful trackers (video players, comments widgets, etc.) with click-to-activate placeholders, and removes outgoing link click tracking on Facebook and Google, with more privacy protections on the way."
Instead of touching the hellsite directly, use the frontend Nitter. Loads much faster, and has less distracting bullshit.
Want to stop some clickbait video or channel from ever showing up in your recommendations? Now you can.
How did I live without this? Automatically skip over sponsorships. Sleep soundly at night knowing that you will never again hear an ad for Raycon earbuds (protip: they're hot garbage) or Raid: Shadow Legends (protip: it's hot garbage).
Bring back one of the casualties of Youtube's continuing war on their users.
Unhook: Remove YouTube Recommended Videos
Does even more that it says on the tin; remove the home feed, sidebars, recommended videos, comments, chat, and more. My second favorite addon.
"LeechBlock NG is a simple productivity tool designed to block those time-wasting sites that can suck the life out of your working day. All you need to do is specify which sites to block and when to block them." Great for breaking the habit of visiting sites that waste your time.
May be a matter of taste. Personally, I can't live without them. Firefox can also be configured to hide the top tabs.
A file archiver that integrates with the file explorer's right click menu. 7z, XZ, BZIP2, GZIP, TAR, ZIP and WIM support. More efficient than WinZip. Can also encrypt archives.
Distributed by Microsoft themselves. Extra options for customizing the behavior of various aspects of Windows. Pin program windows to always be visible, schedule when to wake the machine, copy colors from any window into the clipboard, enable workspaces, extend File Explorer functionality, remap keys and shortcuts, enable bulk rename.
I highly recommend remapping CAPS to CTRL; it's much easier on the pinkie if you're working with an application that has lots of keyboard shortcuts.
Use the classic start menu from Windows 7, 8, 8.1; Toolbar for Windows Explorer; supports skins and can be customized in nearly any fashion.
What's eating your disk space? WinDirStat is a disk usage statistics viewer and cleanup tool that gives you a simple visual infographic representing your disks.
A bit more effort to share files with strangers, but an excellent tool for synchronizing folders between multiple machines, even across operating systems. Because data is only kept on machines you own, and encrypting keys are shared with no one, your files are safe from prying eyes over the network.
It's beyond annoying to bring up some article on medieval history, or ancient Norse, and find that half the symbols aren't covered by your default font. Junicode is a TrueType/OpenType font covering the Latin Unicode ranges, as well as Runic and Gothic.
Fast, small, supports nearly every image format imaginable. Features: Lossless JPG rotation and cropping, batch conversion, overlays, effects, hotkeys, plugins. Surpasses the default image viewer in every possible metric.
Heavily customizable music player; supports MP3, MP4, AAC, CD Audio, WMA, Vorbis, Opus, FLAC, WavPack, WAV, AIFF, Musepack, Speex, AU, SND, and more. Extendable with plugins. The UI can be rearranged to taste.
High performance video player; the feature set is unmatched. I recommend browsing the manual and learning the keyboard shortcuts. You'll wonder how you lived without them. (I frequently use the keys to speed up or slow down video, or advance forwards or backwards frame by frame.)
Fast, stable, free from bloat. Safe from the PDF hacks that use Adobe Reader to install malware.
Manage, tag, categorize, edit, and convert your ebook collection.
By far the best reader on Windows. After installing, run and go to 'Options', then 'Configure'. Move the tab for 'Lanczos quality' all the way to the right. Close the 'Configure' window. Go to 'Options' -> 'Resizing Algorithm'. Select 'Lanczos (better quality)'. This makes most manga look much better, especially if you need to zoom in. You can also change the page direction when reading manga.
Other weather sites pull their information from NOAA to begin with. Skip the middlemen and use the source.
Astronomy Picture of the DayWolfram Alpha Computational Engine
Wiktionary, the Free Dictionary
Webster's 1913 Dictionary Online
See also: You're Probably Using the Wrong Dictionary
The Phrontistery: Obscure Words and Vocabulary Resources
Behind the Name; Etymology and History of Names
The Internet Archive's Text ebook and Text Archive
Nyaa.si - Torrent Tracker for Manga, Anime, etc.
A paid service, but unbelievably more useful than Google. My default search engine.
"An independent DIY search engine that focuses on non-commercial content, and attempts to show you sites you perhaps weren't aware of in favor of the sort of sites you probably already knew existed. The software for this search engine is all custom-built, and all crawling and indexing is done in-house." One of my favorite tools. Returns all kinds of interesting things that you'll never see with Google.
Wikiart - The Visual Art Encyclopedia