A touch PDA is a personal digital assistant with a touchscreen. These days this will often be in the form of an Internet-enabled smartphone. However, there are still some PDAs which do not have either a voice function or an Internet connection.
The name "personal digital assistant" is given to a range of devices which carry out multiple functions such as a web browser, media player and telephone. Generally the name is applied to devices which carry out multiple functions rather than having a primary activity. For example, technically the Apple iPod® is a computer, but because it is primarily a media player it is not usually classed as a PDA.
Today the vast majority of touch PDAs have a telephone function. Such devices are usually known as a smartphone to distinguish them from a standard, less-featured cellphone. Phones which double as a touch PDA are particularly popular with business users, though they are becoming increasingly popular with consumers.
There are a wide variety of touchscreen systems which can be used in a touch PDA. Some simply allow users to press pre-defined on-screen buttons. Others have a virtual keyboard: this can be unwieldy on a small screen, though newer models are easier to use thanks to larger screens, particularly those which can be used in landscape mode. Another touchscreen system allows handwritten input through a stylus or digital pen, with the PDA converting this to text.
It is very common now for a touch PDA to feature some form of Internet access. At its most basic this can be through a system such as WAP which can transfer data across an ordinary cellphone connection, albeit at a very slow speed. More advanced PDAs use the high-speed 3G network to transfer data. Another option is to allow the PDA to connect to a wireless network: this can give higher transfer speeds, but only works when a wireless Internet signal is within range.
Another important feature with a touch PDA, particularly one used for business, is synchronization with a computer. This means lengthy documents can be created on the computer and transferred to the handheld device, rather than typed on the PDA itself. Synchronization is also important for backing up data from the PDA such as contact details and appointments. Depending on the model of PDA, the data can be transferred via a wired connection such as a USB cable, or a wireless method such as Bluetooth®. Most PDAs come with dedicated software for synchronization, though third-party software may offer different features.