Unit Conversion - Converter and Calculator is an iPhone application that offers users an easy and efficient way to convert units. With 16 different unit categories supported, including temperature, currency, distance, weight, volume, and more, the app makes it easy to switch between different types of conversions. Additionally, the app features two calculators, a standard one and a scientific one, so users don't have to switch between different apps.

The app sorts units by frequency of usage, with the most frequently used units appearing at the top of the list, making it easy to access the most commonly used units. The app also features programmable buttons that allow users to save their favorite unit conversions for even faster access. The app even includes a swap key for quickly swapping between two selected units. All of these features are accessible from the main screen, eliminating the need for tedious sub-screen navigation.

One important note is that for currency conversion, rates are downloaded from an internet server, so an internet connection is required for this feature to work. Overall, Unit Conversion - Converter and Calculator is a simple and intuitive app that is perfect for anyone who needs to convert units quickly and easily.