Correct spelling, explanation: it is an Old English word, which evolved from the form alswā to the contemporary form that we know today. It is a common adverb, used in both formal and informal contexts. In a statement, it can appear in various positions, but usually, it appears at the beginning of a sentence and is followed by a comma.

Definition of also:
1. adverb – too, in addition,
She is an English teacher and also a translator.
2. adverb – similarly, That may sound unbelievable, but
I am also taking part in this course.

Collocations and idioms with also:
1. also-ran – a loser, a person who doesn’t win in a competition, Unfortunately, she was an also-ran in the last running competition.
2. not only…but, also – the structure used to relate two things, especially to emphasize the feeling of shock or surprise,
Not only did he forget his homework, but also he turned up late to classes.

Incorrect spelling, explanation: both native users and learners of English make a common mistake in spelling by doubling the letter -l, which gives an incorrect form allso. It is difficult to figure out where the mistake comes from, but probably some users think that the word also is a combination of two English words: all and so. The only correct form, however, is also.

Incorrect spelling

Incorrect spelling