Hey,

By giving civil Services Examination, the UPSC recruits candidates for various Central and All India Civil Service posts in the Indian Administrative Service (IAS), Indian Foreign Service (IFS), Indian Police Service (IPS), Indian Revenue Service (IRS), etc.

For the preparation, the toppers have recommended NCERT books to be the best ones.

• You need to start preparation as soon as possible. You can by the NCERT books online. Downloading free PDFs is possible, but I would recommend hard copy of books is better.
• See the syllabus thoroughly and see which areas you are good at. There are areas like current affairs which need daily practice, you need to read newspapers and watch news daily to get this skills.
• Give mock tests as many as you can. The admission consists of three parts: preliminary objective type test, main descriptive test and personal interview.
• Gain logical reasoning skills by daily practice and improve your observation skills. This will help you during interview.
• You can watch videos on YouTube and learn from byjus application as well. See the type of questions asked.
• You can join coaching if you want.

From this platform, you can get help regarding the application process, registration process, old question papers and other queries.

https://www.google.com/amp/s/competition.careers360.com/articles/upsc-ias/amp

Hope this helps!