Matthew McGiffen continues a series on encryption in SQL Server:
TDE is referred to as a “transparent” form of encryption. What that means is that the process of encrypting and decrypting data is fully performed in the background. The queries we write to access data are unchanged whether TDE is enabled or not. So, enabling TDE has no impact on application functionality, does not require refactoring of code, and is therefore relatively easy to implement. TDE encrypts all the data in a database, so you don’t need to choose which data items to encrypt.
Read on to learn more about it, including specific items TDE does not cover.