A copy of your lists is held in 2 places: One on your phone, the other on the Web Server. When you update the lists on your phone, the copy on the phone is modified. When you update your lists on the Web Server, through a browser on a PC, the copy on the Web Server is updated. Whenever you wish you can synchronize the two lists.
During synchonization the changes made to one copy are applied to the other. The only conflict arises when an entry is modified on both. In this case 2 entries, instead of 1, will appear on the synchonized lists: one for the phone modification, the other for the Web Sever modification. It is then your choice whether you keep both, one or none.
As one copy of your lists is held on the Web Server, this can be accessed and updated from any PC that has an internet connection and Web Browser. However, it is only possible to synchronize with these lists from one phone. As you change your phone you can move the lists from one phone to another, but you cannot use 2 phones with the same list on the Web Server.
The copy of your lists held on our servers is encrypted.