I Did Not Allot a Lot of Time for This Post
So let me get straight to the point. There seems to be a great deal of confusion over this little issue.
Allot is a verb. It means to parcel out, to assign, to apportion. Example: That doctor allots only five minutes to each patient.
A lot is two words. It is a noun phrase and means myriad, bunches, tons, a great number. Example: Five hundred algebra problems is a lot of homework.
Alot is not a word, and anyone (especially anyone purporting to be a professional writer) who allows it to make it into a finished printed piece ought to be strangled with typewriter ribbon. Some grammarians make an exception if one is writing dialogue; I would not recommend this usage, however, unless you are trying to indicate that the character speaking is uneducated or illiterate.