enum('yes', 'no') vs tinyint -- which one to use?

What's the best practice for fields that hold true/false values?

Such columns can be defined as enum('yes','no') or as tinyint(1). Is one better/faster than the other?

Is it better to use enum('1','0') vs. enum('yes','no') (i.e., does it write 'yes' or 'no' as a string to every row so the database storage size gets bigger)?

avoid enum from this reasons

The bottom line is that ENUM has its place, but should be used sparingly. The model should enforce the constraints, not the database; the model should handle interpreting raw data into useful information for your views, not the database.

BOOLEAN type is there for a reason. It is indeed a TINYINT(1) but since it's there, it must be the recommended way.

Also, ENUM is a non-standard MySql extension. You should avoid it, especially if you can achieve the same results in a standard way.