When troubleshooting your Mac, you often need to get information about your system and what's going on inside of it, either to help you identify and fix the problem yourself or so you can convey that information to others who might help.
One tool that can help with this is a utility that used to be called System Profiler but as of OS X 10.7 (Lion) was renamed System Information. By either name, it's a handy app that lets you look up all kinds of details about your system's hardware and software, from the serial number and firmware version of your particular Mac to information about peripheral devices attached to it.
You can access this system profiler in a couple of ways. One is to go to Applications > Utilities and find System Information (or System Profiler if you haven't upgraded lately) and open the program directly from there. Or you can open the Apple menu, click More Info, then select System Report.
In either case, the resulting system report has a list of categories on the left, with detailed information about each category on the right.
While the information in the system profiler may be a bit daunting at first glimpse, there are four key areas that I'd recommend you check out for future troubleshooting.
Battery status and health
If you have a portable Mac and are experiencing problems charging your battery, or if the battery is running out of power sooner than you expect, your battery might actually be damaged or simply worn out. This is especially true if your system is relatively old and its battery is nearing the end of its expected lifetime.
The longevity of a battery is determined by the way it's stored and the way it's used. If you keep the battery stored properly (half-charged, as Apple advises) and do not subject it to extreme temperatures, it will last longer.
When you do use the battery, you need to charge it regularly. Each battery is designed be charged and depleted and still give you more than 80 percent of its initial capacity as long as it is below a given number of full charge cycles--between 300 and 1000 cycles, depending on the Mac model. (A single charge cycle is defined as charging that collectively adds up to a 100 percent charge of the battery's capacity. So if you used up half your laptop's battery one day, charged it up, then did the same thing the next day, that would cumulatively count as one charge cycle.)
To check up on your battery's health in System Information, select the Hardware > Power category, and you'll see Battery Information listed at the top. This includes the charge remaining, as well as the cycle count and the condition of the battery. If this condition says anything but Normal, you should consider taking the system in for service.
Storage device status
Another area on your Mac that might need troubleshooting attention is its hard drive and any attached secondary drives. This primarily includes the drive's capacity and availability, but in addition you might need to find the type of device and details about ownership, formatting, and whether or not the drive is encrypted.
This information can be found in Apple's Disk Utility program, but is also listed in the Hardware > Storage section of System Information.
Connectivity of peripherals
One last thing in the Hardware section you should check out is the part that details the peripherals connected to your system. This can help you troubleshoot daisy-chaining of devices and also properly match device speeds. For example, you can find out if you have a USB 3.0 hard drive connected via a USB 2.0 hub, which would compromise its performance.
This same approach works for FireWire and Thunderbolt connections, both of which have separate sections under the Hardware category. Simply click these to show the connected devices and their corresponding speeds.
You can also see what peripheral devices are demanding the most power from your bus. For each you should see a Current Available and Current Required. So if you have devices daisy-chained and are experiencing problems with one or two dropping out, you can more evenly distribute the load across your various input ports, or find ways to supply alternate power to these devices (such as using a power adapter rather than bus power).
Third-party software installations
You can also look up the software installed on your system in System Information and see which apps are from Apple and which are from third-party vendors. This information can help you troubleshoot problems, especially if the software is a kernel extension; a bug or two in these can affect the entire system.
To see these details, you can select Extensions, Installations, and Applications under the Software category, and then list each by the Obtained From or Source column to see if they are from Apple or another developer.
While this approach is good primarily just for gathering information, it can help diagnose problems you might be having. Prime candidates are kernel extensions, scanning and maintenance tools, security software, parental-control suites, and firewalls.