The study examines the errors committed by second language learners in their writing. It also tracesthe effect of Error Analysis (EA) teaching techniques on ESL students' writing skill. A total of 100 undergraduate students of the Bridge Course at Aligarh Muslim University were the subject of the study. Firstly, a pretest was conducted at the semester beginning where students were asked to write a composition. These write-ups were analyzed and results were saved. In the next stage, students were given multiple activities based on grammar and writing for around 3 months as a treatment. The main focus of the treatment was to look into the specific errors collected in the pretest. After completing the treatment, a posttest was performed to assess any change in type and frequency of errors. Errors of both tests categorized mainly into four types: omission, addition, misformation and misordering. These errors are further analyzed by adopting the notions of Coder's Error Analysis and Surface Strategy Taxonomy as theoretical frameworks. Moreover, acomparison of pretest and posttest results shows significant reduction in the frequency of errors in posttest denoted that treatment had positive effects on the performance of students. Hence, it is expected that through this study, ESL teachers will be more familiar with the most common errors made by students. They will investigate the causes of errors and recommend appropriate solutions. This study will also assist teachers to make more objective decisions about adopting relevant content and teaching strategies to help ESL students learn better.