Working with PDF files: a practical guide

How to create and open PDFs, add comments, fill in forms, merge files, reduce file size and prepare documents for an application, step by step.

A job application, documents for university admission, a certificate for a government service: today most of these are sent as a PDF file. Plenty of people hear “please send it as a PDF” and are not sure where to start. In this guide we cover the practical basics of working with PDFs: what the format is and why it is so convenient for sharing documents, how to create a PDF in Word, Google Docs and on a phone, how to put together a PDF from photos, how to open and read PDFs and add comments, how to fill in forms and add a signature, how to merge, split, rotate and delete pages, how to reduce file size, how to extract text and what OCR is, how to protect a file with a password, how to name files and what PDF requirements you will meet when submitting an application. At the end you will find common mistakes, a practical exercise and a checklist.

Menu names in this guide follow the English interface of each program. Programs are updated regularly, so a button’s name or position may change slightly; if so, look for a similar item in the menu.

What a PDF is and why it is convenient

PDF (Portable Document Format) is a file format that “freezes” a document. If you open a Word file on another computer, the font may be replaced, a table may shift and the page count may grow: it all depends on which program and fonts the recipient has. A PDF stores the text, fonts, images and page layout inside itself, so the document looks the same on a computer, a phone and a tablet.

The main advantages of PDF:

The same appearance on every device. The recipient sees the page exactly as you do.
No special program needed. Any modern browser and most phones open PDFs on their own.
Protection from accidental changes. A PDF cannot be edited with a single click like ordinary text, so the document does not “break” on the way.
Several documents in one file. It is convenient to send a diploma, a copy of your passport and your CV as a single file.

It is worth knowing that a PDF is meant not for editing but for sharing a finished document. So always keep the original file (for example, the .docx): if you need to change the text later, you edit that file and create a new PDF.

Creating a PDF: Word, Google Docs, a phone and photos

In Word

Once a document is prepared in Word, there are two ways to turn it into a PDF:

File → Save As. In the save window, choose PDF in the “Save as type” list, type a file name and click Save.
File → Export → Create PDF/XPS Document → Create PDF/XPS. The result is the same; only the route differs.

The Options button in the save window lets you make a PDF from only some of the pages. Under “Optimize for”, “Standard” gives a high-quality file and “Minimum size (publishing online)” a smaller one.

In Google Docs

In Google Docs, choose File → Download → PDF Document (.pdf). The file goes to the downloads folder on your computer.

On a phone

On a phone, PDFs are usually created through the print function:

On Android, open the document, page or photo and choose Print from the menu (sometimes it sits inside Share). In the printer list at the top, choose Save as PDF, tap the PDF icon and pick where to save the file.
On iPhone, tap Share → Print, then use Share again and choose Save to Files. You can also select several photos in the Files app, long-press and choose Create PDF.

Putting together a PDF from photos

Often a document exists only on paper and you photograph it with your phone. Simple ways to combine several photos into one PDF:

On Windows, select the photos in a folder, right-click and choose Print (in Windows 11 it may be under Show more options), choose Microsoft Print to PDF as the printer and click Print.
On macOS, open the photos together in Preview, arrange the thumbnails in the left-hand panel in the right order and choose File → Print → PDF → Save as PDF.
On a phone, scanner apps save several pages straight into one PDF. This is covered in detail in our article on scanning documents with a phone.

A scanner app does a better job than an ordinary photo: it finds the edges of the page and straightens any skew.

Opening, reading and commenting on a PDF

There are several ways to open a PDF:

A browser. Chrome, Edge, Firefox and Safari open PDFs on their own: just drag the file into the browser window. Edge also has tools for highlighting text (Highlight) and drawing by hand.
Adobe Acrobat Reader. A widely used free program for reading PDFs, with tools for comments, highlighting, filling in forms and signing. Download it only from the developer’s official website or an official app store.
macOS Preview. The built-in program on Mac computers: it is enough for reading, commenting and working with pages.
Phone apps. On Android, PDFs are usually opened by the file manager or Google Drive; on iPhone, by the Files app. There are separate PDF apps too.

Comments and highlighting

A colleague has sent you a draft report as a PDF and asked for your opinion. Rather than retyping the text, it is easier to leave comments. In Acrobat Reader:

Open the Comment tool on the top or side panel.
To mark an important passage, choose Highlight text and drag across the text.
To write a remark, choose Add a sticky note, click where you want it and type your text.
Save the file (Ctrl + S) and send it back.

In Preview, the same actions are in the Tools → Annotate menu. Comments are added on top of the document rather than into the text itself, so the author reviews them and makes the corrections in the original file.

Filling in forms and signing

Some PDFs are fillable forms: they contain fields you can type into, tick boxes and lists. You open such a form in Acrobat Reader or a browser and fill it in by clicking on the fields. When you have finished, remember to save. Some browsers may not keep the data you entered when you close the file, so after filling it in, open the file again and check.

If the PDF is an ordinary (non-fillable) one, the Fill & Sign tool in Acrobat Reader helps:

Open Fill & Sign.
Choose the add-text tool, click above a blank line and type your name, the date or other details.
If a mark is needed, add an “X” or a ”✓”.
Use Sign → Add signature to draw your signature with the mouse, type it or upload a photo of it, then place it where needed.
Save the file under a new name.

In Preview, a signature is added through Tools → Annotate → Signature.

An important difference: a drawn signature versus an electronic digital signature

A signature drawn on a PDF is simply an image of a signature. It does not prove who signed the document or that it has not been changed since: such an image is easy to copy into another document. In many cases, for example an event registration sheet or an internal request, this is enough. But official electronic document workflows use an electronic digital signature (EDS), which is a completely different technology. To learn how it works and when you need it, read our article on electronic documents. Always check with the organisation requesting the document which type of signature it requires.

Merging, splitting, rotating and deleting pages

Built-in and free tools

macOS Preview. Merging: open the first PDF, turn on View → Thumbnails and drag the second PDF file onto the thumbnail panel. You change the page order by dragging. Rotating: select a page and choose Tools → Rotate Left or Rotate Right. Deleting: select a page and press Delete. Splitting: select the pages you need and drag them onto the desktop; they become a separate file.
Microsoft Print to PDF on Windows. Open the PDF in a browser, click Print, choose Microsoft Print to PDF as the printer and enter the pages you need in the “Pages” box (for example, 2-4). This way you save just the part of a large file you need. A browser’s print window also offers “Save as PDF”.
LibreOffice Draw. Part of the free office suite: you can open a PDF, delete and rotate pages, and export the file again.

Online services and privacy

Search the internet for “merge PDF” and you will find many websites that give you a result within seconds of uploading a file. They are convenient, but here is an important warning: when you upload a file to an online service, it goes to someone else’s server. Who owns the site, how long the file is kept and who can see it are usually things you do not know.

Do not upload your passport, ID card, diploma, medical certificate, bank statement, contracts or any other documents containing personal data to an unfamiliar online service. Work with such documents using the built-in tools on your computer. Use online services only for files that are not confidential, such as an event programme or a public announcement. Safe internet habits are covered in detail in our article on online safety.

File size, extracting text and passwords

Reducing file size

A PDF put together from phone camera photos can turn out very large, especially if it has many pages. Many websites and email services limit the size of files you can upload. Ways to reduce the size:

Lower the quality in the scanner or app. A document does not need a very high resolution. Black-and-white or greyscale mode produces a much smaller file than colour.
In Word, choose “Minimum size (publishing online)” under “Optimize for” in the Save As window.
In macOS Preview, use File → Export → Quartz Filter → Reduce File Size. This sometimes lowers the quality too much, so always open and check the result.
Remove unnecessary pages. A blank or duplicate page adds to the size as well.

You need a balance between quality and size: the file should be small, but the text, numbers and stamps must be clearly legible. After compressing, open the file and zoom in on the smallest writing (for example, a passport number or the grades on a diploma).

Extracting text from a PDF and OCR

There are two kinds of PDF. A PDF created from Word or Google Docs contains real text: you can select it, copy it and search it. A scanned PDF, or one put together from photos, is really an image: you see text on the screen, but to the program it is just a collection of dots. Ctrl + F does not work in it and you cannot copy the text.

Turning text in an image into real text is called OCR (optical character recognition). A simple way to do it: upload the PDF to Google Drive, right-click it and choose Open with → Google Docs. Drive recognises the text and creates an editable document. Some scanner apps also have OCR. Always check the result: there may be errors in Uzbek letters, the apostrophe and numbers. For confidential documents, keep the warning above in mind.

Password protection

You can set a password for opening a PDF, so that only someone who knows it can open the file. In Word, tick Save As → PDF → Options → “Encrypt the document with a password” and enter a password. In LibreOffice, the password is set in File → Export as PDF on the Security tab. Do not send the password in the same email as the file; share it through another channel, for example by phone. Keep in mind, though, that many official portals do not accept password-protected files, so do not set a password when submitting an application.

Naming files and application requirements

Naming files

A recipient will not be able to find a file called “Scan_0012.pdf” or “IMG_4583.pdf” among dozens of others. A good name says whose file it is and what it contains: “Karimov_Aziz_rezyume.pdf”, “Rahimova_Nodira_diplom_nusxasi.pdf”. Simple rules:

surname, first name and document type;
an underscore or hyphen between words;
no Cyrillic letters, special characters or very long names, as some systems display them incorrectly;
if there are versions, add the date: “hisobot_2026-10-05.pdf”.

To learn how to keep the files on your computer in order, read our article on organising files.

Typical requirements when submitting documents

Employers, universities and the government services portal set their own requirements for PDFs. The most common are:

A size limit. For each file or for all files together.
Merging into one file. A requirement to upload all documents as a single PDF.
Format. PDF only; photos or .docx files are not accepted.
Legibility. Pages the right way up, sharp and not cut off.

Before submitting, read the requirements carefully and follow them exactly.

Example: Aziz prepares a job application

The following situation is hypothetical. Aziz Karimov is applying to a logistics company in Tashkent. The job advert says: “Send your CV, diploma and a copy of your passport as one PDF file, no larger than 5 MB” (the figure is hypothetical).

CV. Aziz prepares his CV in Word and saves it with File → Save As → PDF. He keeps the original .docx too.
Diploma and passport. He scans them with a scanner app on his phone, in daylight, on a flat table. The diploma with its transcript is two pages; the relevant passport page is one.
Merging. He transfers the files to his computer and combines them into one with a built-in tool. Order: CV, diploma, passport. He does not upload the documents to any online service.
Checking. He makes sure every page is the right way up and rotates the one that is upside down.
Size. The file comes out larger than allowed. Aziz repeats the scan in greyscale, and the size now meets the requirement while the passport number is still clearly legible.
Name. He names the file “Karimov_Aziz_ariza_hujjatlari.pdf”.
Sending. He opens the file, looks through it one last time and sends it. He keeps the original scans in a separate folder on his computer.

Common mistakes, a practical exercise and a checklist

Common mistakes

Sending photos one by one. The recipient has to download dozens of images and put them in order. Combine them into one PDF.
Upside-down or sideways pages. Look through every page before sending and rotate it if needed.
A file that is too large. The portal will not accept it, or the upload takes a long time. Compress it, but check legibility.
Over-compression. The file is small but the numbers are blurry, and the document is sent back.
Keeping only the PDF. If the original .docx is lost, even a small correction means retyping the whole document.
Uploading a confidential document to an unfamiliar website. Your personal data stays on someone else’s server.
Treating a drawn signature as an EDS. An official electronic document may have different requirements.
An unclear file name. Instead of “Scan_0012.pdf”, give it a meaningful name.

Practical exercise

Write a short one-page request in Word or Google Docs and save it as a PDF.
Scan two different paper documents with your phone (for example, a certificate and any official letter).
Merge the three files into one PDF using a built-in tool on your computer: the request first, then the scans.
Deliberately rotate one page, then put it back the right way up.
Check the file size. Reduce it and make sure the text is still legible.
In Acrobat Reader or Preview, mark one passage with Highlight and add a comment.
Use Fill & Sign to add your name and the date.
Give the file a clear name, such as “Familiya_Ism_mashq.pdf”.
Try searching for a word with Ctrl + F on a scanned page, and think about why you get the result you do.

Checklist before sending

Requirements read: format, size, number of files.
All documents in the right order in one file.
Every page the right way up, sharp and not cut off.
The size is within the limit and small writing is legible.
The file name is clear and includes your surname and the document type.
No password set (unless one was specifically requested).
Confidential documents not uploaded to online services.
Original files saved in a separate folder.

Working with PDFs is part of everyday digital literacy: once you have learnt it properly, you will be able to prepare applications, certificates and reports in a few minutes. If you would like to learn computers and office software systematically, our computer literacy programme is a good place to start.

Take a look at our association’s free training programmes. When you are ready, submit an application and our specialists will get in touch.