Here's why:
* "Also" is an adverb and typically acts as an introductory word.
* Introductory words generally do not require a comma unless they create a long or complex phrase that could confuse the reader.
Example:
* Correct: Also, the weather was beautiful.
* Incorrect: Also, the weather was beautiful.
Exceptions:
* Very long introductory phrases: If the phrase following "also" is very long or complicated, you might consider a comma for clarity.
* Example: Also, after carefully considering all the options, we decided to postpone the meeting.
In summary: It's best to avoid a comma after "also" at the beginning of a sentence unless the phrase that follows is exceptionally long or complex.