If I want to show a website or a word document to students, I can open it on my laptop (connected to my projector) activate Doceri on my iPad, and my iPad will show what is on my computer screen. I can then annotate, drawing my students' attention to certain features, or pass my iPad to a student who can annotate for us.
In addition, Doceri has a recording feature that will allow me to develop flipped lessons. I can put together a slide show using Keynote or a similar program, run it on my computer mirrored to my iPad, and then annotate with my finger or stylus while recording the lesson and my voice.
Doceri has a variety of annotation tools, is intuitive to use and has been very reliable.