Getting photos from your iPhone to your PC isn't difficult if you use Apple's iTunes software to make the transfer. But if you'd prefer to not use iTunes -- because your iPhone can only be connected to one computer's iTunes at a time -- there are plenty of other ways to get your content onto a PC.
Using Windows Explorer
You don't have to use iTunes to transfer photos from your iPhone to your PC -- you can simply grab them using Windows Explorer.
Step 1: Connect your iPhone to your computer using a USB cable.
Step 2: Unlock your iPhone. You will see a pop-up message asking if you would like to allow this computer to access your photos and videos. Tap Allow to let your computer see the photos and videos on your iPhone.
Step 3: Open Windows Explorer and navigate to your Apple iPhone (if you can't find this, it should be under This PC). You will see a disc called Internal Storage. Double-click this icon to open your phone's internal storage, and then double-click the folder called DCIM to see your phone's photos and videos (they may be arranged in various folders).
Step 4: Transfer your photos from your iPhone to your PC by dragging them onto your desktop.
Backing up Your Photos with iCloud
Every iPhone comes with 5GB of free cloud storage space in Apple's iCloud. This storage space can be used to back up things like phone settings, contacts, and, of course, photos and videos. If you install iCloud's desktop client on your PC, all the photos you take on your iPhone will be automatically uploaded to your PC.
Step 1: Enable iCloud on your iPhone by opening up the Settings app and tapping iCloud. You will need to sign in using your existing Apple ID and password (the same ID and password you use to make purchases from the App Store).
Step 2: Turn on photo syncing in iCloud by going to Settings > iCloud > Photos. If you want all of your photos to be saved and synced to iCloud, turn on iCloud Photo Library. There are a few other settings here that you can turn on if you like: My Photo Stream automatically uploads the last 1000 photos taken on your iPhone to iCloud; Upload Burst Photos uploads your "favorite" photos selected from a burst-mode shot; and iCloud Photo Sharing allows you to create albums to share with friends, family, and publicly on the Internet.
Step 3: Download and install iCloud on your PC from this link. Sign into iCloud using the same Apple ID and password as you used on your iPhone. If you'd prefer to simply access your photos from the web, you can login to iCloud.com to see your photos and other iCloud backups.
Backup Your Photos with Dropbox, Google Drive, or Another Cloud Service
iCloud is convenient, but it's not everybody's cloud storage service of choice. Luckily, some other cloud storage services, like Dropbox, OneDrive and Google Drive, have automatic iPhone photo backup built into their iOS apps.
Step 1: Download and install Dropbox's iOS app.
Step 2: Login with your Dropbox account. If this is the first time logging into the Dropbox app, you will have the option to Enable Camera Upload on the next screen. Tap this and allow Dropbox to access your photos. If you have logged into the Dropbox app before, go to Settings > Camera Upload. Turn Camera Upload on and allow Dropbox to access your photos. Your photos will be uploaded to your Dropbox folder whenever your phone is connected to Wi-Fi (unless you turn on Use Cellular Data, in which case your photos will be uploaded in real-time).
For Google Drive:
Step 1: Download and install Google Drive's iOS app.
Step 2: Sign into Google Drive with your Google account. If this is your first time signing into the Google Drive app, you'll have the option to turn on photo and video backup on the next screen. Tap Turn On and choose the size you would like your photos and videos to be uploaded at -- "High Quality" photos will be smaller than the original photos, but they will not count against your Google Drive storage, while "Original" photos will be the original photos, but will count against your Google Drive storage. Allow Google Drive to access your photos, and your photos will automatically be backed up whenever you are connected to Wi-Fi.
If you have logged into the Google Drive app before, you can find the photo backup settings by going to Settings > Photos and turning on Google Photos folder.
For other cloud storage services:
If your cloud storage service of choice does not offer automatic photo backup via their app, you may still be able to back up your photos using IFTTT, an automation service that lets you connect apps, web services, and devices together.
Step 1: Sign up for IFTTT.
Step 2: On your iPhone, download IFTTT's IF app and login with your IFTTT account. Open the IF app and tap the icon that looks like a bowl in the upper right corner, and then tap the Settings icon in the lower right corner. In the Settings menu, tap Channels and then search for 'iOS Photos'. Tap the iOS Photos icon and tap Connect.
Step 3: Open IFTTT on your computer. Click Channels and search for the cloud storage service you want to use. Box, Evernote, Dropbox, Google Drive, Flickr, and Seagate Personal Cloud can all be connected. Click the icon of the cloud storage service you want to use to connect it to your IFTTT.
Step 4: Search for a photo backup recipe in the search bar. For example, if you want a recipe that backs up your iOS photos to Box, search for "iOS Photos Box." You'll find lots of recipes created by other members (you can also create your own recipe, if you can't find what you're looking for, but that's a bit more complicated). Click on the recipe you want to use and click Add to add it to your recipe box. Once you set up any variables that the recipe uses (for example, naming the folder that your photos will be saved to), your photos will automatically be uploaded to your cloud storage service.
Email Them to Yourself
If you just have a couple of photos you want to transfer to your computer and you can't seem to find a USB cord, you can use the tried-and-true method of emailing them to yourself.
Step 1: Open the Photos app on your iPhone. In gallery mode, tap Select in the upper right corner. Tap the photos you want to transfer (you can only send five photos at a time via email) to select them, and then tap the upload icon in the lower left corner of the screen.
Step 2: Tap the Mail icon to open up your Mail application. In the Mail app, type your email address into the To section and tap Send in the upper right corner. You will need to confirm that you are okay sending the message without a subject, and you will also need to choose what size photos you want to send (small, medium, large, and "actual size").
Step 3: Open your email account on your computer and download the photo attachments to your desktop.