It helps you monitor your progress as your vocabulary in a foreign language such as English, Spanish, Portuguese, German, Italian, French, etc.
Imagine it as a little notebook to record the words or expressions you have just learned helping you keeping track of them. During the next days you can access them, see their definition in your favorite dictionary, search images and related results at Google’s site will be just one tap away. Helping you memorize all words, you had registered.
You can choose the word based on a book you are reading, a TV show or YouTube channel you are watching, or even a video game you are playing.
Add the new word, search for its meaning at the moment, or later.
The best part of the app is it does not suggest any word. You pick all the words yourself. The words you enter are meaningful for you. They can come from a podcast you like, a book that you like, or TV series, etc. If you type in notes fields the original sentence were you first seen the word, it will be easier to you to remember the emotion of the scene, the context where it was used and so on. Making it much easier to remember and incorporate it into your own vocabulary.
If you already use some flash card app such as Anki, for example, try ProgLingo.