も(mo) — Also, Too, Both/And, Emphasized Quantity

• 山田さんは学生です。私も学生です。

  Yamada-san wa gakusei desu. Watashi mo gakusei desu.

  Mr. Yamada is a student. I am also a student.

  も replaces は here (私は → 私も)

• 肉も魚も好きです。

  Niku mo sakana mo suki desu.

  I like both meat and fish.

  N1 も N2 も = both N1 and N2

• 昨日は10時間も寝ました。

  Kinou wa juujikan mo nemashita.

  Yesterday I slept for as long as 10 hours.

  number/quantity + も stresses that the amount is surprisingly large

• ・Stacking rules: も replaces は, が, を (never がも, をも). BUT it stacks onto に, で, へ, と (日本にも行きたい - I want to go to Japan too).
• ・Absolute Negation: Question word + も + negative verb = 'none at all' (誰もいない - no one is there; 何も食べない - I eat nothing).
• ・Double Inclusion: Aも Bも applies the statement to both equally.

Commonly confused with

The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones も is tested against.

• は (wa) — Topic & Contrast Particle
• が (ga) — Subject Marker & Exhaustive Listing
• を (o) — Direct Object & Traversal
• に (ni) — Target, Time, and Existence Location
• で (de) — Context of Action (Location, Means, Condition)
• と (to) — And (Exhaustive), With, and Quotation
• か (ka) — Question, Or, and Uncertain Identity
• の (no) — Possession, Modification, & Nominalization