Are you planning for trek and yet to pack everything?
Let me help you with essentials..
If you are going with Group:
1) Trekking Shoes, must for your trek. If you are doing Sahyadri trek then Action trekking shoes is best option else you can check for waterproof shoes. Even action trekking can be used in Himalayan trek depending on your trek difficulty
2) Water Bottle and/or Water bladder
3) 50 to 60 Litre backpack with Rain cover and one 20ltr day pack which can be used for Summit
4) Warm layers which include Main Jacket, Fleece & T-shirt for day and Thermal for Night (For Sahyadri one jacket is sufficient)
5) Full Sleeve T-Shirt or Shirt and if you are using half sleeves then with inner
6) Trek Pant with One extra pair other than what you are wearing and Undergarments as per necessity
7) Sunscreen, Cap & sunglasses and additional Woolen cap for Himalayan trek
8) Waterproof hand gloves for Himalayan Trek
9) Pair of Socks as per trek days and one pair of Woolen socks for Himalayan Trek
10) Head Lamp with extra pair of Batteries
11) Raincoat and Rain pant if it's monsoon in Sahyadris and for Himalayan trek always
12) Trekking Pole
13) Moisturizer, Lip Balm, Toilet paper; making use of wet tissues should be avoided and if you use please bring back with you at base for disposal.
14) Spoon, plate or Tiffin box with Mug
16) Quick drying Travel Towel and napkins
Other Optional Things:
1) Camera with additional batteries and Memory Card
2) Power bank for mobile charging
3) Knife for emergency
4) Camera Bag and Dry bag for camera
5) Floaters
Additional Things for Personal Plan:
1) Tents depending on size of group
2) Food material
3) Tent light
4) Sleeping bag with sleeping mat
5) Rope and Whistle in case of emergency
6) Map of trek for everyone and also location details where everyone will reach in case of everyone gets separate in emergency
7) Emergency contacts of Local
8) Technical setup material as per difficulty of trek