Consider the following scenario for a form with two fields "Full name" and "email".
When user starts editing the "Full name" field I will not allow user to start editing "email" field until "Full name" conforms to something like "at least two titleized words consisting only of latin letters".
Is it a good practice to force user enter correct data into field? By "forcing" I mean do not allow progress to other entry fields until the first one is filled correctly.
Update As @Jeroen pointed out this enforces the certain order for filling in the fields. As to my scenario - I have no preference over the order of filling in fields. It's just that if user started editing email, he/she won't progress anywhere else if email field is not filled correctly. To sum it all up: user can start with any field, but progress only when that field is filled correctly.