One of the more exciting (yet imperfect) features on the HTC One M9 and a major part of the new Sense 7 is the use of themes. Back in the day it would take some pretty serious hackery to theme a phone. Then custom ROMs started to bake in theming. And finally the manufacturers have gotten into the game. If you've never been into theming your phone, this is a good time to take a look. So ... let's take a look.

Applying themes on your phone We've all changed up the wallpaper or ringtone on our phone. But what, exactly, is a theme? It's that, of course. But throw in a couple more parts — fonts and icons. All of that rolled into a tight little package is what makes a theme. You can get to the themes for the M9 (and future HTC devices) either from the dedicated "Themes" app, or from the "Personalize" section of the settings menu. (The "Themes" app itself is actually part of the "Sense Home" launcher, so you won't actually find "Themes" in the app manager.) Verizon is offering the Pixel 4a for just $10/mo on new Unlimited lines From there, things are pretty self-explanatory. You'll begin by seeing all of the themes lumped together. You get a thumbnail of the main screen, along with the theme's name and whether it's free or paid. (We've only seen free themes thus far, but HTC assures us that paid themes are coming at some point.) You can sort themes by categories, if you like. They are: Abstract, Animals, Architecture, Artistic, Design, Fantasy, Illustration, Nature, Photography, Travel & Adventure, Others, Gaming and Lifestyle. Tap into an individual theme and you'll be greeted by what very much looks like something you'd see in an app store. There are screenshots, ratings, date, size and download statistics, plus a description of the theme and the user who uploaded it. You're also able to rate themes — and you're able to rate them on sight only, no having to download and actually try the theme first. (There are arguments for and against that, of course.) You'll also find icons to share the individual theme, or you can bookmark it for later reference. If you can download an app, you can apply a theme. It's that easy. Applying a theme is pretty straightforward. Just hit the download button, then then hit "Apply." To apply a different theme, you just go through the process again. This is an all-or-nothing application, though. You'll be applying all parts of the theme wholesale. Wallpaper, accent colors, icons, fonts and sounds. We'd love to have the option to apply just the parts we want. (But on the other hand, we get how that would sort of break up the experience.) You can, however, individually browse, download and apply the various parts of themes separately by hitting the hamburger menu (aka the drawer, or the three horizontal lines in the top left). If you want to go back to the default HTC theme, you'll find it (and the other themes you've downloaded) in the "My themes" section.

Create your own theme Using someone else's theme is just half the fun, of course. You can also make your own themes. And there are a couple ways to do it.

Probably the easiest is to use your phone. You start creating a theme by tapping the plus symbol on the main screen. (Until you tap it you really have no idea what it'll do. That could use some work.) You pick an image to use for the home screen, and then the theme engine picks the accent colors based on your image. You can pick a filter for the image itself, if you want, and you'll also get to pick from several pre-designed theme styles. But you can further edit the colors, icons, sounds and font, if you wish — and you'll need to use this deeper "Edit" section if you want to apply a wallpaper to other parts of sense, Such as the messaging app, lock screen and app drawer. (That part is pretty buried, especially given how easy it is to use in its web-based counterpart. And even more buried is the search function. It's at the top of the drawer once it's opened.) From there, give your new theme a name and then save it, and you're done. (Note that you can't edit a theme once you've saved it.) What you can't yet do from the phone is upload your theme back to the community. For that you'll need to head over to themes.htc.com, where you'll basically go through the same process, only on a website.

The web-based theme engine is split into a couple parts. There's the basic "Theme Maker," which includes everything you can do on the phone (and lets you add an image for a Dot View case). There's also a "Maker Pro" option that lets you upload custom images and ringtones in addition to the other options. (It's not entirely clear why that's broken into a separate section, though. Why not just keep it all under one roof?)

Once you've got your theme all worked out, you'll add metadata and upload it to the community. And the usual community guidelines are in place — you'll have to avoid someone else's intellectual property, and no nudity (full or partial, whatever that means; and technically there's already a "tastefully sexy" theme in there could be questionable), plus nothing violent or libelous or discriminatory or otherwise bad. It'll be interesting to see how well HTC is able to police this. One other fun little feature is the ability to follow individual users. So if you find someone who makes themes you really like, you'll be notified when they have a new one. That's pretty cool. And that, as they say, is that. It's a pretty full-featured theme engine and community (though the app could use a little work), that should only grow as more folks start to use it.