So it's a standard in basically every address form out there and I'm questioning why?
Address Line 2. It's in every form that asks for address details. It's never actually seemed necessary to me. It requires another field in the database and all the goofy maintenance that goes with it. Every time you use an address, you have to concatenate it and 99% of the time line 2 is empty. The other 1% of the time you could've just put it into line 1.
Instead of calling it line 2, couldn't it be called something with clearer semantics... like "apartment number"?
It ruins the semantics of the whole address concept. You don't really know what you have in either field. Except maybe that the concatenation of the two fields results in a "plain old address". But "Line 1" and "Line 2" themselves don't really have any meaning. Is something "supposed" to go in each respectively? I've never seen it. Why don't we have address line 3 while we're at it?
I've been thinking about it and realized that as a result, I don't really trust the address data in my database. The whole field is flaky in general because you can't really do validation on it (some addresses have roads and a house number, others have streets and avenues). Except these days you could do something like validate the field against a geolocation api. But simply because of the "Line 2" thing, you can't really be certain what you're doing. Should I combine the (line 1 + line 2), then validate? What do I do with the users original input if I'm correcting them ("did you mean xxx")? Do I just say, "yah, address line 2 doesn't really do anything... I just took your validated input and dumped it into line 1." Why am I even giving the end user (and myself) the chance to be confused.
The way I see it, the field should either be an address (street + house number), or if we're going to split things up, do it properly and ask for the road and house number independently.