• Basic forms
• 増す — to increase; to grow / base form
• 増します — increases / masu form
• 増した — increased / ta-form
• 増して — increasing and… / te-form
• 増さない — does not increase / negative
• 増せば — if it increases / conditional
• Common uses
• 勢いが増す — gain momentum
• 関心が増す — interest increases

増す（ます） is a godan verb. It describes an increase in **degree, intensity, or level**, often abstract.

• Basic forms
• 増やす — to increase; to add / base form
• 増やします — increase; add / masu form
• 増やした — increased; added / ta-form
• 増やして — add and… / te-form
• 増やさない — do not increase / negative
• 増やせば — if (you) increase / conditional
• Common uses
• 数を増やす — increase the number
• 収入を増やす — increase income

増やす（ふやす） is a godan verb. It means **actively causing an increase** — the transitive counterpart to 増す.