The acidic strength of phenols depends on the stability of the phenoxide ion formed after losing a proton.

1. Electron-Withdrawing Groups (EWG): Groups like nitro ($-NO_2$) withdraw electron density via resonance ($-R$) and inductive ($-I$) effects, stabilizing the phenoxide ion and increasing acidity. The effect is stronger at para and ortho positions compared to the meta position.
2. Electron-Donating Groups (EDG): Groups like alkyl ($-CH_3$) release electron density via the inductive effect ($+I$) and hyperconjugation, destabilizing the phenoxide ion and decreasing acidity.

Therefore, the typical order of acidic strength is: $p$-Nitrophenol > $m$-Nitrophenol > Phenol > $p$-Cresol (Methylphenol).