I've rooted my phone. Now what? What do I gain from rooting?

Question

This is a common question by those who have just rooted their phones. What apps, ROMs, benefits, etc. do I get from rooting? What should I be doing now?

Answer 1

Things that Require Root

Root File Explorers

You can remount your /system/ directory read-write, which will allow you to remove carrier-shipped applications you don't like and so on. Root file explorers can allow you to view all folders on your phone, such as /data/ which is normally protected.

• Root Explorer
• ES File Explorer

Tethering

Some devices already have Wi-Fi tethering out-of-the-box, like the Samsung Galaxy S, so this isn't such a big deal on them unless the carrier charges for the feature.

• Android Wi-Fi Tether
• Wireless Tether

Screenshots

root is needed for screenshots before 4.0-Ice Cream Sandwich.

• ShootMe
• Dropcap2

Backups

• Titanium Backup - Back up all of your applications and data. Also allows you to uninstall system apps, integrate updates into your ROM to save space, and so on.
• ClockworkMod Recovery - Usually requires root to install via ROM Manager. Allows you to backup the entire device, including your ROM, as well as flash new ROMs and other advanced tasks.

Application/Network Control

• AdFree - Removes ads by changing the hosts file (so both ads in apps and in browser)
• Droid Wall - Firewall application. Got an app that's using up all your data when you're not even using it? Block it with this!
• Orbot - Tor app
• Cache Mate - Clear cache of all apps
• Droid VNC Server - Connect to your phone via VNC
• LBE Privacy Guard - Selectively remove permissions from app
• Titanium Backup - Back up all of your applications and data. Also allows you to uninstall or freeze system apps, integrate updates into your ROM to save space, and so on.
• Bloatfreezer - Freeze or remove system apps
• Link2SD - Move (system) applications to a second partition in SD card, liberating loads of free space in /system partition.
• Button Savior - Helps to add on screen button to compensate a failure of a physical button.
• ClockSync - to automatically sync the device's time with few predefined atomic clocks.

USB On The Go features

• StickMount - Automatically mount USB flash drives, keyboards, mouse via USB OTG cable.

CPU Control

• SetCPU - Control the processor speed of the phone, can also setup profiles. It allows underclocking based on conditions, e.g. underclock to 125mhz when screen is turned off. It dramatically increases battery life without affecting performance (when you're actually using apps / the phone) or can improve performance via overclocking.
• Overclock Widget - Similar to SetCPU but less functional

Custom Kernels

One popular set of kernels is those provided by ChevyNo1. You can also download them via the premium version of the ROM Manager. Make a nandroid (ClockworkMod) backup before using these kernels! You'll also want to get SetCPU to make the most out of these kernels.

Start with the low voltage kernels at the lowest speed and work your way up to the 1.2ghz. If your phone is stable up to the 1.2ghz range, then try some of the ultra low voltage kernels. If you start getting force closes, then switch back to a low voltage kernel.

Basically each phone (of the same phone brand/model) varies by which kernel it can handle due to the manufacturing differences between processors. So I may have a Motorola Droid that can run ultra low voltage kernels and yours may not be able to run them. These phones weren't necessarily designed to run like this.

Advanced and Miscellaneous

• ROM Manager - Facilitates installing new ROMs with ClockworkMod Recovery, and allows you to back up your entire device (ROM + apps + data) and other advanced tasks.
• Quick Boot - Allows you to reboot into recovery or the bootloader / Download Mode.
• LED Hack - Disable LED on phone (no longer available on Android Market)
• Lag fixes - Various tweaks and filesystem changes to speed up your phone or prevent issues with your phone pausing / freezing temporarily. These are particularly useful on some Samsung phones that use an RFS filesystem. An Ext4 lagfix like Voodoo is recommended, but there are also Ext2 lagfixes like RyanZA's One Click Lag Fix which also allows you to change advanced memory, Wi-Fi, and disk scheduling options.
• Sideloading apps. Most carriers/phones allow this option but AT&T does not.

ROMs

CyanogenMod is a very popular rom that many people put on their phones. It is also easy to install via the ROM Manager app. First install the Clockwork recovery. Then run a backup before you flash any roms.

Also check out "Where can I find stock or custom ROMs for my device" or the XDA forums for other custom roms. Most devices have a specific "Android Development" sub-forum where ROMs are posted.

Always do a nandroid backup before installing any rom or mod! You may also need to wipe all data and cache from your phone before installing or upgrading a ROM.

Answer 2

In few words, rooting an Android system means overcome the limitations that were imposed over it by the manufacturer. People may want that for different reasons, but the main one is freedom. Having a rooted phone means you've got all the control over your device.

The main reason people root phones is to install a custom ROM. Custom ROMs are often known for improvements in performance and exclusive features that are not present on manufacturer ROMs, like installing apps on sdcard or taking screenshots. Custom ROMS can also become a system update alternative for those devices that were abandoned by their manufacturers. You can see a review of popular ROMS, as an example, here.

Rooting Android also allows you to uninstall stock apps that you don't use or don't want, besides those that violates user's privacy (see CarrierIQ). Another main reason for doing that is to gain more space on internal storage.

A rooted device lets you install almost any app that requires root access. Those apps generally aim to do something that would not be possible without that privilege. A lot of useful apps were shown on the previous answer, but you may find a lot more available on Google Play. You can find a list of good apps here.