It's all about the phones at Mobile World Congress 2014 (pictures)

Whether it's a $25 Firefox phone, or the highly anticipated Samsung Galaxy S5, phones are the main attraction at Mobile World Congress in Barcelona this week. Click through to see the highlights of the show, including phones from big players like LG and Nokia, as well as devices from emerging companies. We'll be updating this slideshow throughout the week as new phones emerge.

Samsung's newest flagship phone, the Galaxy S5, sports a 16-megapixel camera and a HD 1080p screen, and is chock-full of new sensors. One of the star features is the fingerprint scanner, which can unlock the device with a quick scan. There's also a heart rate monitor built into the flash that can come in handy while you exercise. Check out the full rundown of the Galaxy S5 on CNET.

Though Samsung unveiled the Galaxy Grand 2 in November 2013, the company finally gave the press some hands-on time with the phone at MWC. The Grand 2 is a follow-up to the first Galaxy Grand, which was shown off at Mobile World Congress in 2013. This phablet is almost a dead-ringer for Samsung's Galaxy Note 3, down to the plastic back cover fashioned to look like leather with stitching around the edge.

The Grand 2 has a 5.25-inch, 1,280x720-pixel display, a (slow by today's phablet standards) 1.2GHz quad-core processor, and an 8-megapixel main camera. Get the full run-down on the Galaxy Grand 2 on CNET.

Another device in Samsung's lineup, the Galaxy Core LTE is a smaller, less expensive model that still packs LTE power. The smartphone has a 4.5-inch screen, which looks tiny compared to the Note 3, but it's much easier to use one-handed. There are no pricing details yet, but Samsung says the Core LTE will be much cheaper than the company's premium offerings, such as the Galaxy S5. It'll launch in the UK in the next few months. Read more about the Galaxy Core LTE.

Though it's a not a huge step up from its predecessor, the Xperia Z1, Sony's Xperia Z2 does offer a few worthwhile improvements. It sports a larger 5.2-inch screen and a slightly faster 2.3GHz Qualcomm processor. It's running the freshest version of Android, 4.4.2, and has a camera that shoots 4K video.

The Z1 never made it to the US, so don't expect the Z2 to either. However, Sony gave the US the Z1S at CES this year, so we may see a version of the Z2 come to America.

Sony also introduced the Xperia M2, an less expensive Android smartphone that's not waterproof, at MWC 2014. The M2 sports a 1.2GHz quad-core processor, a 960x540-pixel display and an 8-megapixel camera. It's not nearly as impressive as the Xperia Z2, but it's said to cost much less than that flagship phone.

HTC debuted a plastic version of the HTC One at Mobile World Congress, called the Desire 816. The device is considered to be the company's flagship midrange phone. It comes with a HD 5.5-inch display, a 13-megapixel camera, LTE support, and a satisfyingly sturdy plastic body. You get to choose from four colors; black, white, orange, and teal.

The lower-end model in the Desire line, the 610 still packs impressive features. It's running Android 4.4 KitKat, has a 4.7-inch, 960x540-pixel display, and supports LTE.

The LG G Pro 2 is LG's follow-up to the Optimus G Pro from 2013. The new phone is running Android 4.4, is powered by a quad-core Snapdragon 800 processor, and has a bright 5.9-inch screen.

Following the trend of paired-down versions of flagship phones, LG launched the G2 Mini at Mobile World Congress. Along with a smaller body, the G2 Mini has more modest specs, including a Snapdragon 400 processor and an 8-megapixel camera. Its 4.7-inch qHD IPS display isn't as sharp as the G2's, but it has the benefit of running Android 4.4 KitKat. Read more about the G2 Mini on CNET.

The top of the line in LG's L series, the L90 packs a 4.7-inch IPS display with a reasonable 960x540 pixel resolution. Though the phone supports only 3G connectivity, it's running Android 4.4 KitKat. Other specs include a a 1.2GHz quad-core Qualcomm processor, 1GB of RAM, 8GB of internal storage, and an 8-megapixel rear camera.

LG's entry-level offering from MWC is the F70. This modest phone has a plastic body with a 4.5-inch WVGA display, a 1.2GHz quad-core processor from Qualcomm, and a 2,440mAh removable battery. It also has LTE support and runs Android KitKat.

Nokia's first Android phones aren't like other Android phones. The Nokia X (and its brothers, the X+ and XL) run a special, modified version of Android that looks nothing like what you'll find on a Droid or Galaxy phone. In fact, the operating system looks like a mashup of Android and Windows Phone, which isn't surprising given that Nokia has been making mostly Windows Phone devices for the last few years.

The Nokia X won't wow most folks with its features, but it's a good fit for developing smartphone markets with its 4-inch screen with an 800x480-pixel resolution, 3-megapixel camera, a 1GZH dual-core Qualcomm Snapdragon processor, and Assisted GPS. It also costs just 89 euros.

The X+ is identical to the X, except it comes with more onboard storage and an SD card slot. The XL is slightly larger than the X and has a 5-megapixel camera. You can read more about all three phones on CNET.

A new addition to Nokia's Asha line, the 230 is a budget-minded device with a tiny touch screen. In fact, the touch screen measures just 2.8 inches with a 320x240-pixel display. Like other Asha phones, it's running Nokia's Asha operating system and comes in a variety of neon colors. It'll cost just 45 euros when it hits global markets in the first week of March.

Going back to its candy-bar-style phone roots, Nokia released the 220 at MWC, a simple phone that has physical keys and no touch screen. There are a few apps, including Nokia's Express Cloud browser, but this phone is much closer to Nokia's past feature phones than it's current smartphone lineup. It will sell for just 29 euros when it goes on sale in March.

This phablet from ZTE clocks in at just over 6 inches with its 720p HD screen. The Grand Memo II LTE is powered by a Snapdragon 400 processor and runs Android 4.4. Other specs include a 3,200mAh nonremovable battery, 2GB of RAM, and 16GB of internal memory. Compared to other phablets on the market, which sport superfast processors and crisp 1080p screens, the ZTE Grand Memo II LTE falls a bit flat.

Blackberry kept it low-key at MWC 2014, but still managed to introduce two new phones, the Z3 and Q20. We're light on details for both phones, but we know that the Z3 is an all-touch screen model that will run the latest version of Blackberry's mobile OS, BB 10.2.1, and come with a battery that promises lots of juice.

We have even less details on the Q20, except that it will have a keyboard similar to the Q10. We'll have to wait until the second quarter of this year to get more information on the new phone.

Not to be confused with the Alcatel One Touch Idol 2, the One Touch Idol 2 S is one of the top-of-the-line offerings from Alcatel. While the two phones come with the same brushed metal design and similarly-sized 5-inch IPS displays, the Idol 2 S packs a better HD resolution of 1,280x720 pixels. It also has a quad-core 1.2GHz Qualcomm Snapdragon 400 processor, with LTE capabilities.

Along with the Idol 2 S, Alcatel released a quirky new phone called the Pop Fit that comes with an armband. While you can make calls on the Pop Fit, the device is really geared at fitness, with Runkeeper pre-installed and JBL headphones included in the package. You can also swap out the colored back plate to customize the phone to your tastes.

One of the higher-end devices in Alcatel's Firefox phone lineup, the One Touch Fire S shares the same chassis as the Idol 2 Mini S. For 169 euros, you get a Firefox phone with LTE, a quad-core 1.2GHz processor, and an 8-megapixel camera.

A followup to the underwhelming Acer Liquid E2, the Liquid E3 has a big 4.7-inch screen and a sharp 13-megapixel camera. Powering the phone is a quad-core 1.2GHz processor backed up by 1GB of RAM and 4GB of internal storage. It's priced at a midrange 199 euros.

Just a few months after the first YotaPhone debuted at CES in 2014, the second-generation of this e-ink device emerged at MWC. Though it's just a prototype, the new YotaPhone gets a much higher resolution screen, jumping from 640x360 to 960x540. That makes reading on the secondary e-ink screen much easier, as words are sharper. That e-ink display will also become completely touch-sensitive to swipes.

Huawei's first Firefox phone is the Y300. It's sporting a dual-core 1GHz Snapdragon 8225 processor, 512MB of RAM, and 4GB of storage, and is running Firefox OS v1.1.

It won't turn any heads with the younger set, but that's because the Yezz Andy AZ4.5 is an Android phone aimed at seniors. It has a special version of Android with large tiles that make it easy to place a phone call or search the Internet.

The Emporia Smart could help you during an emergency. The Android phone has an emergency button on the back that dials 911 (or other emergency hotline) or another preprogrammed number. It also features a few other quirky details, including a stylus and large physical buttons on the front.

For anyone who's hoping to keep their data safe and secure, look to the Blackphone from Geeksphone. This Android-based device comes with tons of security features to keep your data and activity safe from prying apps. It also has a 4.7-inch IPS screen with a 1,280x800 resolution, a 2GHz quad-core processor with 2GB of internal RAM, and 16GB of onboard storage. Read more about what makes the Blackphone so secure on CNET.