Okay, here is my experience.
1) boys often talk later than girls
2) if you are concerned, ask your Pediatrician
3) Do NOT compare him to other children...or feel 'awkward' that your child is not talking like other kids or feel that your kid is 'weird' or certainly do NOT feel that way in front of other parents
4) If your Pediatrician is not concerned, try not to worry too much. BUT as a parent, you can do what I did....
My Son sees a Speech Therapist who comes to our home, he started this from about 19-20 months old. The services are FREE...through the zero-to-three program through the Easter Seals outreach program in my town. My son had a complete overall assessment... and, there is NOTHING wrong with him and in fact he is even advanced developmentally in some areas. And his comprehension of what he hears and what we tell him is excellent. BUT, he is just slow to talk, per his typical age group. But, since it is free, I figured why not? My son has made great strides and progress because of it. There is absolutely NO pressure on the child or parent. We are free to stop anytime WE want. It is very low key. My son enjoys it very much, and he is "proud" anytime he says something new. PLUS, they give the Parents knowledge and ways to help your child's speech.
Now, per our speech therapist, she said that there is indeed a gender difference in when a child starts talking. About 80% of her clients are boys. Nothing clinically 'wrong' with them...but this is typical.
Now, if you are concerned about your son... or his other developmental areas, you can contact your local regional center about getting free services. Your Pediatrician should know about this as well and tell you who/where to call. You do not have to be referred by a Doctor. And, these services assist in any developmental area, not just with speech. It's really great, being it's free. I find it very valuable and helpful for any child/family that can use its help.
There are certain techniques and ways you can 'help' a child to form words and talk. It is just not about talking, but their mouth/tongue/throat coordination too. For example, some children who have food issues or cannot eat certain things, also may have speech problems.
Again, an assessment is helpful for any concern you have. For my son, I have seen it's benefits and the smiles on his face when he says 'new' words. He loves when his Speech Therapist visits us and he'll run to the door to let her in. It's really nice.
All the best,
Susan