Annotations are marks that you put on top of a document. With a tablet or a computer, you can take a picture of a document then put marks on it. That could mean text or handwriting in different colors. It could also mean highlights or notes.
SnapType Pro Best of Class Author’s Pick
With this app, you take a picture of a document and then type on a picture of the document. The fact that this app streamlines the process makes it an awesome app.
https://itunes.apple.com/us/app/snaptype-pro/id1124123246?mt=8
https://play.google.com/store/apps/details?id=com.snaptypeapp.android.pro
iAnnotate 4 — PDFs & more
This is an annotation app that gets some good ratings.
https://apps.apple.com/us/app/iannotate-4-pdfs-more/id1093924230
ClaroPDF
This is a free annotation app with some very good reviews.
https://itunes.apple.com/us/app/claropdf/id666770153
GoodReader PDF Editor & Viewer
This is an annotation app that is also good at organization. The app has been around for a long time and gets some good ratings.
https://apps.apple.com/us/app/goodreader-pdf-editor-viewer/id777310222
PDF Expert by Readdle
This is a highly rated annotation app.
https://itunes.apple.com/us/app/pdf-expert-6-read-annotate-edit-pdf-documents/id743974925?mt=8
ClaroPDF Pro
This is a paid annotation app with some good reviews.
https://apps.apple.com/us/app/claropdf-pro/id633997623
Xodo PDF Reader & Editor
This app annotates PDFs and open Word documents.
https://play.google.com/store/apps/details?id=com.xodo.pdf.reader
https://itunes.apple.com/us/app/xodo-pdf-pro-highlight-sign-search-take-notes-edit/id805075929?mt=8
Annotations
This app allows you to label important notes with different colors. It helps you stay organized.
https://play.google.com/store/apps/details?id=com.mv.notas&hl=en