[Android Q&A, Help & Troubleshooting] scoderx0e:
Make phone calls

Services that cost you money

This permission is of moderate to high importance. This could let an application call a 1-900 number and charge you money. However, this is not as common a way to cheat people in today's world as it used to be. Legitimate applications that use this include: Google Voice and Google Maps.

Another important point to note here is that any app can launch the phone screen and pre-fill a number for you. However, in order to make the call, you would need to press [Send] or [Call] yourself. The difference with this permission is that an app could make the entire process automatic and hidden.

Send SMS or MMS

Services that cost you money

This permission is of moderate to high importance. This could let an application send an SMS on your behalf, and much like the phone call permission, it could cost you money by sending SMS to for-pay numbers. Certain SMS numbers work much like 1-900 numbers and automatically charge your phone company money when you send them an SMS.

Modify/delete SD card contents

Storage

This permission is of high importance. This will allow applications to read, write, and delete anything stored on your phone's SD card. This includes pictures, videos, mp3s, documents and even data written to your SD card by other applications. However, there are many legitimate uses for this permission. Many people want their applications to store data on the SD card, and any application that stores information on the SD card will need this permission. You will have to use your own judgment and be cautious with this permission knowing it is very powerful but very, very commonly used by legitimate applications. Applications that typically need this permission include (but are not limited to) camera applications, audio/video applications, document applications

WARNING: Any app targeting Android 1.5 or below (possibly 1.6 as well) will be granted this permission BY DEFAULT and you may not ever be warned about it. It is important to pay attention to what version of Android an app is targeting to know if this permission is being granted. You can see this on the Market website in the right hand column.

Read contact data, write contact data

Your personal information

This permission is of high importance. Unless an app explicitly states a specific feature that it would use your contact list for, there isn't much of a reason to give an application this permission. Legitimate exceptions include typing or note taking applications, quick-dial type applications and possibly social networking apps. Some might require your contact information to help make suggestions to you as you type. Typical applications that require this permission include: social networking apps, typing/note taking apps, SMS replacement apps, contact management apps.

Read calendar data, write calendar data

Your personal information

This permission is of moderate to high importance. While most people would consider their calendar information slightly less important than their list of contacts and friends, this permission should still be treated with care when allowing applications access. Additionally, it's good to keep in mind that calendar events can, and often do contain contact information.

Read/write Browser history and bookmarks

Your personal information

This permission is of medium-high importance. Browsing habits are often tracked through regular computers, but with this permission you'd be giving access to more than just browsing habits. There are also legitimate uses for this permission such as apps that sync or backup your data, and possibly certain social apps.

Read logs / Read sensitive logs

Your personal information / Development Tools

This permission is of very high importance. This allows the application to read what any other applications have written as debugging/logging code. This can reveal some very sensitive information. There are almost no reasons an applications needs this permission. The only apps I might grant this permission to would be Google apps. The name of this permission recently changed as it came to light how important and dangerous this permission can be. Both the old name and category and the new name and category are listed above.

Read phone state and identity

Phone calls

This permission is of moderate to high importance. Unfortunately this permission seems to be a bit of a mixed bag. While it's perfectly normal for an application to want to know if you are on the phone or getting a call, this permission also gives an application access to 2 unique numbers that can identify your phone. The numbers are the IMEI, and IMSI. Many software developers legitimately use these numbers as a means of tracking piracy though. This permission also gives an application to the phone numbers for incoming and outgoing calls.

WARNING: Any app targeting Android 1.5 or below (possibly 1.6 as well) will be granted this permission BY DEFAULT. And you may not ever be warned about it. It is important to pay attention to what version of Android an app is targeting to know if this permission is being granted. You can see this on the Market website in the right hand column.

(see image above)

Fine (GPS) location

Your location

While not a danger for stealing any of your personal information, this will allow an application to track where you are. Typical applications that might need this include (but are not limited to) restaurant directories, movie theater finders, and mapping applications. This can sometimes be used for location based services and advertising.

Coarse (network-based) location

Your location

This setting is almost identical to the above GPS location permission, except that it is slightly less precise when tracking your location. This can sometimes be used for location based services and advertising.

Create Bluetooth connection

Network Communication

Bluetooth (Wikipedia: Bluetooth) is a technology that lets your phone communicate wirelessly over short distances. It is similar to Wi-Fi in many ways. It itself is not a danger to your phone, but it does enable a way for an application to send and receive data from other devices. Typical applications that would need bluetooth access include: Sharing applications, file transfer apps, apps that connect to headset out wireless speakers.

Full internet access

Network Communication

This is probably the most important permission you will want to pay attention to. Many apps will request this but not all need it. For any malware to truly be effective it needs a means by which to transfer data off of your phone; this is one of the settings it would definitely have to ask for.

However, in this day and age of cloud computing and always-on internet connectivity, many, many legitimate applications also request this.

You will have to be very careful with this setting and use your judgment. It should always pique your interest to think about whether your application needs this permission. Typical applications that would use this include but are not limited to: web browsers, social networking applications, internet radio, cloud computing applications, weather widgets, and many, many more. This permission can also be used to serve Advertising, and to validate that your app is licensed. (Wikipedia article on DRM).

View network state / Wi-Fi state

Network communication

This permission is of low importance as it will only allow an application to tell if you are connected to the internet via 3G or Wi-Fi

Discover Known Accounts

Your accounts

This permission is of moderate-high importance. This allows the application to read what accounts you have and the usernames associated with them. It allows the app to interact with permission related to that account. An example would be an app that was restoring your contact, would discover your Google account then send you to Google's login screen. It doesn't actually get to see your password, but it gets to work with the account. This is also legitimately used by applications to add contacts to your accounts, such as dialer replacements and contact managers/backup/sync/etc.

Manage Accounts

Your accounts

This permission is of high importance. This allows the application to manage the accounts on your phone. For instance it would be used by a service like Facebook to add an account to your accounts list. It seems at this time unclear if this permission allows an app to delete accounts.

Use Credentials

Your accounts

This permission is of high importance. This will allow an application authorization to use your accounts. They do this typically by giving what's called an AuthToken depending on what account you use (Google/Facebook/Yahoo/Last.fm/Microsoft/etc.). It's not as scary as it sounds however, it does typically protect your password from being seen by the application. However, it's still a very important permission you should give only with great caution.

Read/modify Gmail

Your messages

This permission is of high importance. Few apps should need access to your Gmail or email account. Email is also a prime method for managing accounts with other companies and services. For example, someone with control over your email could request a new password from your bank. While this is the worst case scenario, and there are various legitimate uses for this permission, it's still best to treat all email related permissions with extreme care.

Install Packages

System tools

This permission is of critical importance. This allows an application to install other applications on your system. This can be exploited by virus writers to install adware and malware on your system without your knowledge. It is a very, very dangerous permission and should almost NEVER be granted to a typical app. The only legitimate uses for this permission are for Market-like apps such as the Amazon AppStore or the Android Market.

Prevent phone from sleeping

System tools

This is almost always harmless. Sometimes an application doesn't expect the user to interact with the phone directly, and therefore may need to keep the phone from going to sleep. Many applications will often request this permission. Typical applications that use this are: Video players, e-readers, alarm clock 'dock' views and many more.

Modify global system settings

System tools

This permission is pretty important but only has the possibility of moderate impact. Global settings are pretty much anything you would find under Android's main 'settings' window. However, a lot of these settings may be perfectly reasonable for an application to change. Typical applications that use this include: volume control widgets, notification widgets, settings widgets, Wi-Fi utilities, or GPS utilities. Most apps needing this permission will fall under the "widget" or "utility" categories/types.

Read sync settings

System tools

This permission is of low impact. It merely allows the application to know if you have background data sync (such as for Facebook or Gmail) turned on or off.

Restart other applications

System tools

This permission is of low to moderate impact. It will allow an application to tell Android to 'kill' the process of another application. However, any app that is killed will likely get restarted by the Android OS itself.

Retrieve running applications

System tools

This permission is of moderate impact. It will allow an application to find out what other applications are running on your phone. While not a danger in and of itself, it would be a useful tool for someone trying to steal your data. Typical legitimate applications that require this permission include: task killers and battery history widgets.

Control Vibrator

Hardware controls

This permission is of low importance. As it states, it lets an app control the vibrate function on your phone. This includes for incoming calls and other events.

Take Pictures & Video

Hardware controls

This permission is of moderate importance. As it states, it lets an app control the camera function on your phone. In theory this could be used maliciously to snap unsuspecting photos, but it would be unlikely and difficult to get a worthwhile picture or video. However, it is not impossible to make malicious use of cameras.